score:9
Middle and end of the 19th century could be characterized as follows.
Strong European countries such as Great Britain, France, Spain, Portugal, Russia and other countries were expanding rapidly in the uncharted territories such as Africa, India, China, the Philippines, and Japan because they need to increase their trade and plunder natural resources from weak nations. The US was a late comer to this ever-intensifying competition and East Asian countries (China, the Philippines and Japan) were the only territories left for the US to compete with other European nations. China, through two Opium Wars, was weakened significantly and had to accept Western countries' power and influence, which led to the collapse of the Qing Dynasty.
After the Independence War, the US was not capable of invading or colonizing other countries due to the lack of leadership and resources (it was not as powerful as other European nations). Throughout the middle of the 19th century especially after slavery abolition (note that the slave trading and cheap labor provided by slaves were two of the biggest contributors to the U.S. economy), the U.S. had to find another way to increase its trade. After China's borders were forced to open, it was a golden opportunity for the U.S. that it could never miss.
Even though other countries in East Asia were either opened or colonized by European nations (except for a few including Korea), Japan was one of the few countries (including Korea) that have never been opened by European countries. Japan was strategically very important to the US as it was the geographically closest to the US and it still remained closed without much influence by Western countries.
The US had to force Japan to open up its border so that it could take a strategic position and use Japan's land and resources to improve its trade and economy.
From Japan's perspective, Japan watched what happened in China and it could not risk weakening itself as China did through the wars. Japan needed Western technology and weaponry to defend itself. That's why Japan had to take the offer made by the US.
Conclusion:
Why would some nations want to force Japan to end their isolation?
Because they needed Japan as a trading base and gateway to China, India and other countries such as the Philippines. Japan was one of the few countries that have not been technically colonized in East Asia. Its strategic importance was too great to be overlooked by any country, especially the U.S.
Upvote:3
If you google your question, you'll find multiple answers, the best of which begins with the following:
There were several reasons why the United States became interested in revitalizing contact between Japan and the West in the mid-19th century. First, the combination of the opening of Chinese ports to regular trade and the annexation of California, creating an American port on the Pacific, ensured that there would be a steady stream of maritime traffic between North America and Asia. . . . US Department of State
(aside: If you want to know why the USA implements a given foreign policy, the US State Department is probably a good source).
The source goes on to list additional reasons:
Upvote:6
The importance of Japan grew in relation to the China trade. The importance of the latter grew after China lost the Opium War in 1840-42, and was forced to open a number of treaty ports to European countries.
Two countries in particular had an interest in Japan: America, and Russia. That's because Japan represented a "way station" to China for those two countries. For example, the distance between San Francisco (newly founded in the 1840s) and Tokyo is 5100 miles; from there to Beijing is 1300 miles. Similarly, Japan stood astride communication lines between Vladivostok and the Chinese coast.
A hostile Japan could deny either country, particularly Russia, access to the Chinese coast; a friendly Japan could guarantee access.