By mid-1945, was Japan capable of maintaining the war even in the absence of further direct American attacks?

I think the possible answer could fall into how to tread the OP's word "capable of maintaining the war"....

Thus I would like to analyze between the "material capability side" and the "spiritual capability side".

Material Capability Side

1. From this source

Data comparison ( From 1941 to 1945 )

The number of soldiers ( including civilian related employees of each army )

JIA

1941 2.42 million

1945 8.26 million

The U.S

1941 1.88 million

1945 12.297 million

( Hereunder let me call million --> mil ( and the abbreviated explanation will be subject to the former ( 1941's ))

The number of ships ( including small size ships )

JIA

1941 148mil tons ( The number of vessels 385 ),

1945 70.8 mil ( 341 )

The U.S

1941 131.3mil ( 341 vessels ),

1945 427.2mil ( 918 )

The number of airplanes

JIA

1941 4,772

1945 10,938

The U.S

1941 12,240

1945 40,810

The shift of volume of critical materials ( This site looks first funny but if you follow the link, you can find the numbers ( but the difference between 1940 and 1945 )

Oil

JIA

1940 30 million tons

1945 22 mil

The U.S

1940 18,286.7 mil

1945 23,175 mil

Iron

JIA

1940 365.8 million tons

1945 103.9 mil

The U.S

1940 4,302.7mil

1945 4,985.5 mil

So, I was able to find only some critical materials and military power in terms of the comparison and time shift, --- apparently from the first and foremost there were huge gap between the JIA and the U.S and in 1945 the gap widened helplessly.

Spiritual Capability side

Why I would like to this was because of the mentality among Japanese then, who almost made a determination to fight even if they die in case the U.S force would have landed on the homeisland. The above link, is explaining Ketsugou Sakusen, in English Operation Ketsugo, almost equivalent to the whole Kamikaze attack by the whole Japanese.

Since ( I don't know the reason why ) I can not copy the Chinese characters, so I can not copy the original sentence, but if you believe in me, according to the above link,

1. JIA already expected the U.S forces would land on the homeisland around the fall of 1945, already in early 1945 which coincidentally same with the expected first strike by the Operation Downfall by the U.S army.

2. Now let's take a look at the Japanese site ( about the operation Ketsugou )

You can see the number 2800 ( actually it means 28 millions ), even if you can not read Japanese.

This is the number of Kokumin Giyu Sentotai, in English, Volunteer Fighting Corps, ( and the link is in English ), which is a civilian forces, and as the link says

The Kokumin Giyū Sentōtai would be organized, if the Allied landing unit close to the Japanese homeland. Governors of Prefectures could conscript all male civilians between the ages of 15 to 60 years, and unmarried females of 17 to 40 years

Conclusion

So I think you might have been able to picture some kind of image what kind of situation the then Imperial Japan was at.

Conscripting men from 15 years old to 60 and women from 17 years old to 40, respectively? Considering the number of the entire population then ( including that of Korea, and Manchuria, ) was around 80million, I would like to call this "operation" was an "entire Kamikaze defense" by the then Imperial Japanese.

So in terms of the production of materials and army capability, it was almost impossible, but when considering the huge loss of the U.S soldiers by the above mentioned "entire Kamikaze attack", well, I might be able to say the JIA was --capable-- to defend or fight.

Have a nice day.

There's three questions here.

1. Was Japan a threat?
2. If not, could it be a threat again?
3. Would Japan surrender without the atomic bomb or invasion?

These are aspects of the larger question, "was the atomic bomb and invasion necessary"? That's a big question with lots of moving parts that's still debated by professional historians, so it's good to reduce the discussion down to a few pieces. That means ignoring, for the purposes of this question, issues like the geopolitical situation between the US and the Soviet Union, or the economic and political realities of maintaining a blockade, or the morality of invasion and atomic weapons.

They're still big questions.

Was Japan a threat? To the US? No. To mainland Asia? Yes.

As far as the US was concerned, Japan could not operate outside their island or coastal waters. The simple answer is fuel.

You can have all the people and tanks and planes and guns you want, if you have no fuel you cannot conduct an offensive. You need fuel for hours and hours of training pilots and sailors, untrained pilots will be chopped to pieces. You need fuel to transport all that stuff around to staging areas. You need fuel to get them to the battle area. You need fuel during the battle. You need fuel for all the supply and support ships and aircraft.

Japan had very little fuel left, very little home production, and no more imports coming in. Japan needed hundreds of millions of barrels of oil for their military in 1944. They produced 1.5 million. Their merchant fleet was destroyed by US submarines and aircraft, down to a fifth what it was at the start of the war. There was nothing for those tankers to haul, their overseas oil conquests had been recaptured or cutoff.

The best Japan could hope to do is harass the US with kamikaze tactics. While they were an excellent means of taking advantage of untrained pilots and obsolete aircraft, they were not an offensive capability. Nor could they drive off the Allies. The Battle Of Okinawa demonstrated that if the Allies wanted to be somewhere, they could despite everything Japan could throw at them. The kamikaze air threat would diminish as the Japanese supply of fuel, trained pilots, and air-worthy aircraft continued to be drained.

OTOH, Japan was a threat to China, Formosa, Manchuria and Korea, or at least it could still do tremendous damage. Being a land based war, they could still operate effectively without fuel. There remained a large Japanese army fighting in mainland Asia in 1945, and it was doing some very nasty things. The sooner that war was over, the better.

Could Japan be a threat again? No. Again, fuel and other industrial raw materials. Once her stockpiles were gone, Japan would have to rely on her minuscule domestic production. A blockade would effectively send her back to an agrarian state. Imagine North Korea without Chinese support.

Even with materials, the rapid pace of Allied military technological improvement would render her militarily impotent. Radar, rockets, jet aircraft, computers, missiles... these were all just becoming available to the Allies in 1946. Japan would have none of these advances.

Would Japan surrender without the atomic bomb or being invaded? That is, could Japan have been blockaded into surrender? As far as I know, that question remains unresolved. I'll do my best to follow the more concrete line of materials.

Materially, blockade meant certain malnutrition and disease, but not necessarily starvation. In another topic I answer why the UK had enough to eat in WWII, but Japan's situation was far, far worse. Her blockade was total, she had no allies, her civil management was poor, her housing and transportation crippled by bombing and there was little fuel to move things around anyway. A third of her people were homeless (compared to 5% in Britain) and she was producing 2/3 the rice as at the beginning of the war with no imports and only coastal fishing. And with no fuel for heating, thousands would freeze in the winter of 1945.

While there's no indication of mass starvation in 1945, in order to survive under a blockade, feed the people and prevent an uprising they would need to shift significantly to an agrarian economy. To get the necessary manual labor (remember, no fuel) and training would mean demobilizing large portions of the military.

This presents a Catch 22. Demobilize the military and you're open to invasion. This would also have the psychological effect of making the population question why they're persisting at war anyway if they can't make war; why not surrender and get back to life? Demobilization would send a signal to the people that Japan had lost the war. It would also weaken the position of the military within the government allowing a peace faction to negotiate surrender.

On the other hand, if you keep a strong military you can't feed and house the people. Mass misery and starvation makes it difficult to prevent an uprising. And it doesn't matter how willing you are to fight, you can't do it without food.

I believe Japan under blockade would have become weaker every month either by starvation, internal strife, or demobilization. This would eventually have lead to uprising, surrender or a much easier invasion. It's nice to think of a sort of peaceful Miyazaki-esque agrarian Japan sealing herself off from the world again, but as soon as she let her guard down the Allies would invade to end the costly blockade.

References for fuel numbers.

• Empire Of Japan Database
• The Pacific War Encyclopedia Online
• Military Production and Imports of Japan in WWII
• Oil Conversion Factors (7.33 barrel are a ton).

You can never be sure that a naval blockade will indeed lead to a national collapse. E.g., Britain did not surrender. Why do you think Japan would have?

You must also remember the international situation: what if the SU would land in Japan and occupy it? By mid-1945 is was already a fact that, despite numerous agreements and promises of free elections, SU was turning Poland into its communist satellite. What if US troops would be required elsewhere? This is the same answer to the common question: why did SU fought to eliminate the surrounded 6th Army instead of waiting for it to collapse.

Finally, you are forgetting the other side of the equation: how much effort would be required from the US to keep Japan blockaded? This includes not just the fleet necessary to isolate the islands from the continent, but also the "insurance fleet" in case Japan built new warships. The pressure to "finish the war quickly and bring the boys home" is very strong in any democracy.

Japan was not really capable of "maintaining war" by mid-1945. The problem was that it was unwilling to "make peace" on anything like reasonable terms.

If the Allies had wanted a stop to the fighting, one possibility might have been a "cease fire in place." That would leave the Allies in possession of the Philippines, and Iwo Jima and Okinawa, but it would also leave Japan in control of large parts of China, which would have given Japan a strong base from which to start a future war. Basically, the Allies would not have agreed to a peace in which Japan had any overseas possessions, and Japan would not agree to a peace in which it lost all its overseas possessions, and was confined to the homeland.

It was only when the homeland itself was threatened that Japan agreed to surrender the Home Islands and relinquish the overseas possessions. Otherwise, there would have been a bloody conflict for each of these overseas territories.

The answer to this question is yes, Japan was capable of maintaining the war at the time and likely would have done so. However, Japan was incapable of conducting meaningful offensive operations by then. So, in a sense they couldn't have hurt the U.S. but they would have hurt many others.

U.S. General Curtis LeMay was responsible for implementing the highly effective but controversial strategic low-level incendiary bombing campaign and a crippling minelaying campaign in Japan's internal water ways. These two initiatives alone devastated Japan's war production to such an extent that only meager production remained by mid 1945.

In interviews after the war, LeMay stated that the bombing missions would have been out of targets by September, 1945. In an NBC interview he concluded that by that time he couldn't see much of a war going on.

See https://en.wikipedia.org/wiki/Curtis_LeMay#World_War_II

However, large numbers of Japanese troops remained in China and several other areas in Southeast Asia. Though they were receiving few supplies, they still had significant defensive capability and were a real danger to the civilian populations in those areas which they controlled.

As it was, Japan almost didn't capitulate even after the two atomic bombs were dropped, so strong was the military control over the government. Only after Emperor Hirohito, who was considered a god by his people, broke a tie vote on whether to surrender or not, did they finally do so. Even then, a group of junior officers attempted a coup d'etat to stop his orders from being broadcast to the country the next day.

The Pacific War was a long and costly affair for the U.S. as well. Japan, knowing they couldn't defeat America, hoped to cause so many casualties that its people would insist they end the war without Japanese surrender. Doing so would have been a victory for the military faction in Japan.

It can be argued that the U.S. could have just stopped short of the atomic bombing. Though my statement here is only my speculation, because it didn't happen. It is my belief that anything short of what the U.S. settled for in regards to Japan would have been a huge mistake. That regime had to be stopped forever as the war lords would have re-built as soon as they could. Or just as bad, Japan would have become another conquered territory of the Soviet Union. Neither of which is a suitable outcome.

No. Japan had almost no capability to continue waging war. In fact, strangled by the American blockade, Japan was tottering on the brink of collapse. Experts both then and since believed that the combined pressure of the Soviet entry, the relentless blockade (and usually, the conventional aerial bombardment campaign) would have compelled Japan to surrender. The only real question is when.

There is no real doubt that Japan was essentially defeated by 1945. The Japanese military had no means of countering either the Red Army or Allied bombers. Both of these are commonly cited as factors in speeding up a Japanese surrender, but more importantly, as an island nation dependent on the sea lanes for basic survival, Japan was doomed by her disastrous naval defeats.

Shortly after the war ended, the United States Strategic Bombing Survey undertook an investigation of the Japanese leadership in the last months of the war. They concluded that:

Based on a detailed investigation of all the facts, and supported by the testimony of the surviving Japanese leaders involved, it is the Survey's opinion that certainly prior to 31 December 1945, and in all probability prior to 1 November 1945, Japan would have surrendered even if the atomic bombs had not been dropped, even if Russia had not entered the war, and even if no invasion had been planned or contemplated.

Now, the Survey can certainly be accused of overstating their case here. Japan could well have lasted into 1946. However, it is a virtual certainty that Japan would have collapsed eventually due to the blockade alone. The rice harvest in 1945 was disastrous - some 40% short of normal levels. Japan was heavily reliant on imports even during the best of times, but that option was no longer available by 1945. A cabinet report, reproduced in the Survey's findings, bleakly states:

The food situation has grown worse and crisis will be reached by the end of this year. The people will have to get along on an absolute minimum of rice and salt required for subsistence.

Tellingly, even after the war Japan tethered on the brink of starvation for several years. Despite renewed access to imports and the massive logistical support of the Americans, Japan still could not adequately feed itself in a time of peace. Had the blockade kept up (not to mention Soviet invasion and Allied bombing campaigns), the picture would have been far more bleak.

1945 produced the worst harvest in Japan for a generation ... before 1942, Korea, Taiwan and China had provided some 31 per cent of rice imports, 92 per cent of sugar and 25 per cent of salt.

_{- Pike, Francis. Empires at War: a Short History of Modern Asia Since World War II. IB Tauris, 2011.}

While Allied leadership did not know the precise extent of Japanese privations, the overall picture was clear. For example, Admiral Earnest King, the American Chief of Naval Operations, was convinced that the Navy would have starved Japan into surrendering.

The President in giving his approval for these [atomic] attacks appeared to believe that many thousands of American troops would be killed in invading Japan, and in this he was entirely correct; but King felt, as he had pointed out many times, that the dilemma was an unnecessary one, for had we been willing to wait, the effective naval blockade would, in the course of time, have starved the Japanese into submission through lack of oil, rice, medicines, and other essential materials.

_{- King, Ernest; Whitehill, Walter Muir. Fleet Admiral King: A Naval Record. New York City: W. W. Norton & Company, 1952.}

The fact is, by 1945, Japan was on its last legs. Its cities were reduced to ashes, its economy ruined, and basic necessities for both war and civilian livelihood were almost depleted.

By mid-1945, largely because of America naval operations, Japan's merchant fleet had been reduced to about 10 percent of its prewar size, its oil supplies cut to under 3 percent of the prewar peak, most imports of foodstuffs, oil and other materials blocked, and Japan's economy was in shambles. Food supplies had perilously dwindled, with sharp cuts in food rations in 1944 and again in 1945.

_{- Hixson, Walter L. The American Experience in World War II: : The Atomic Bomb in History and Memory. Vol. 7. New York: Routledge, 2003.}

Even without the conventional bombing, Japanese industrial capacity had virtually collapsed simply due to the lack of natural resources. Japan could neither feed itself nor equip its armies to fight, and with access to the outside world cut off by extensive mines and submarine warfare, there was no realistic way it could rebuild.

[B]y the summe rof 1945 output from Japan's factories was in free-fall across all sectors. Aluminium production fell to 9 percent of peak output while steel and oil refining fell to 15 percent. Monthly aircraft (mainly kamikaze) production, whose output the Japanese government sought to maintain at the cost of everything else, still fell by over 40 percent between 1944 and 1945 ... the mining of Japan's seaways by B-29s, which cut off the import of raw materials and involved no loss of civilian life, was just as effective as urban bombing in reducing Japan's industrial output.

_{- Pike, Francis. Hirohito's War: The Pacific War, 1941-1945. Bloomsbury, 2015.}

It is popular to claim that Japan would somehow fight on due to their mythical fanaticism. Aside from smacking of racism, such claims ignore the very real fact that Japan did in fact surrender rather than fight to the death. Ultimately, Japan by mid-1945 was a thoroughly defeated nation that would soon be incapable of feeding itself, much less equip its armies for war.

Japan's situation was manifestly incomparable to British case.

Britain was fed by the whole of her empire and the United States. Japan's overseas conquests were either lost or rapidly being overrun. Britain was supplied by a huge merchant marine and the shipbuilding capabilities of the Free World. Japan's merchant marine was in the bottom of the Pacific. The Royal Navy was supreme in the open seas and could keep Britain's lifelines open. The Imperial Japanese Navy had virtually ceased to exist.

Take the differences in British and Japanese merchant marine for example. By the war's end, Japan's merchant marine had been reduced to less than 1.5 million gross tonnes, barely a quarter of its prewar strength. In contrast, Britain commanded a Merchant Navy of 15 million gross tonnes while a staggering 40 million sailed under the American flag.