He then investigated the connection between the Soviet Comintern and left wing organizations in the United States while serving in Latvia, Lithuania, and Estonia.

[citation needed] In 1933, the Roosevelt Administration extended diplomatic recognition to the Soviet Union and Henderson was assigned to Russia to help reopen the U.S. Embassy in Moscow.

Aiding him in this task were fellow junior officers George F. Kennan and Charles Bohlen, who along with Henderson would later be considered the Department's top Soviet specialists.

Henderson argued that the French bombing undermined not only the newly created United Nations but also the West's relations with the Arab world.

[7] Henderson came under fierce criticism from San Francisco attorney Bartley Crum, who had served on the Anglo-American Committee of Inquiry formed to examine political, economic and social conditions in Mandatory Palestine and to make recommendations for both short-term and long-term solutions to problems in the region.

[8] In late 1946, the Kremlin attempted to bully Ankara into ceding territory in eastern Turkey and control of the Dardanelles, which would have given Moscow its long-desired warm water port.

Henderson, with Acting Secretary of State Dean Acheson, convinced Truman to express support for Turkey and to dispatch navy units to the eastern Mediterranean.

[citation needed] In 1947, the British embassy in Washington informed Henderson that the United Kingdom was no longer able to bolster the pro-Western forces against the Communist agitators in the Greek Civil War.

Henderson designed the Truman Doctrine plans to strengthen Greece and Turkey, an early move which would influence U.S. containment policy for decades to come.

The United States was opposed to the nationalization,[11] and he helped orchestrate the 1953 CIA-assisted coup which removed Mossadegh, a democratically elected leader.