Why didn't United States replace Mohamad Rezā Shāh with another king during the 1979 revolution?

England has always pursue same targets in iran:

1. oil & gas.

2. breakdown of iran.

3. dispute iran's with neighbors.

4. impose backward leaders to iran. (khomeini, naseredin shah...)

5. Discord between iran and U.S.A (Iran's hostage crisis).

6. stop iran's development (Islamic (backward) revolution).

7. creating divisions within Iran (Green revolution). and so on...etc.

What benefit have accrued to the U.S?

change kingdom regime of iran into fundamentalist regime stop iran's development and its nuclear plan for more than 34 years,

Why didn't United States replace Mohamad Rezā Shāh with another king during the 1979 revolution? This way, why during Iran's revolution the Carter's administration had arranged for the shah to leave Iran? Why didn't they replace him with another king?

Concise answer:

Since, they weren't able to do so. Because the revolution of Iran was as an Islamic revolution which was doing and supporting by majority of people strongly (approximately 98/2%) and in truth, they didn't want another king ... / So, there were striving to reach Islamic government ... and factually the US were aware that they are missing Iran.

Otherwise I assume, what ... can be solely a kind of excuse(s), since they weren't able to keep the reign..., otherwise they would keep kingdom ..., because they never like Islamic government, since such government could be deemed as a kind of obstacles against their profits and goals.

More info. regarding Iranian Revolution

The Iranian Revolution (also known as the Independence and Liberty Revolution or the 1979 Revolution;[4][5][6][7][8][9] Persian: Enqelābe Esteqlāl wa Āzādi, 'Enqelābe Esteqlāl wa Āzādi') refers to events involving the overthrow of the Pahlavi dynasty under Mohammad Reza Shah Pahlavi, who was supported by the United States[10] and its eventual replacement with an National republic under the Grand Ayatollah Ruhollah Khomeini, the leader of the revolution, supported by various leftist and Islamic organizations[11] and Iranian student movements. Demonstrations against the Shah commenced in October 1977, developing into a campaign of civil resistance that included both secular and religious elements[12][13][14] and which intensified in January 1978.[15] Between August and December 1978 strikes and demonstrations paralyzed the country. The Shah left Iran for exile on January 16, 1979, as the last Persian monarch, leaving his duties to a regency council and an opposition-based prime minister. Ayatollah Khomeini was invited back to Iran by the government,[16][17] and returned to Tehran to a greeting by several million Iranians.[18] The royal reign collapsed shortly after on February 11 when guerrillas and rebel troops overwhelmed troops loyal to the Shah in armed street fighting, bringing Khomeini to official power.[19][20] Iran voted by national referendum to become an Islamic Republic on April 1, 1979,[21] and to approve a new theocratic-republican constitution[12][13][22][23] whereby Khomeini became Supreme Leader of the country, in December 1979.

To see the complete text, refer to the following source:

• https://en.wikipedia.org/wiki/Iranian_Revolution

The two situations were completely different: in 1943 Iran was largely occupied by the Allies (British and Russian) who thus had the final say in everything. Whereas in 1979 the Shah was toppled by a genuine revolution; at that stage there was nothing the US could have done for him. Perhaps if he had abdicated himself a few years before 1979 in favour of, say, his son, things could have worked out.

One must point out that the US did intervene in 1954 to topple Mossadegh, the Prime Minister - with the Shah connivance. However, that was also a different business.

As for the idea that the Ayatollah was an American creature—frankly, that's risible. But let's try to seriously engage with the idea and ask some questions about it:

1. What would have been the American motive? Since the Shah was an American creature of sorts himself, the US would need a serious motive to replace him with such an unstable and unknown quantity.

2. Are there any other examples of the US installing fundamentalist rulers anywhere? I don't think so.

3. What benefits have accrued to the US from the Ayatollah's regime? Nothing much, except a lot of grief and trouble.

4. In the more than 30 years since then, has any evidence of US collusion in the Ayatollah's rise come to light? Not that I know of.

So, this idea has to be dismissed out of court, upon examination.