negotiations with the AIOC in July 1951, after the AIOC threatened to pull its employees out of Iran, and Britain warned tanker owners that "the receipts from the Iranian government would not be accepted on the world market." The British ratcheted up the pressure on the Iranian government and drew up a detailed plan of an invasion to occupy Abadan, code named "Buccaneer". That plan was ultimately rejected by both Clement Attlee and Winston Churchill. US President Harry S. Truman and US ambassador to Iran Henry F. Grady opposed intervention in Iran but needed Britain's support for the Korean War. The United States believed it was possible to reach a face-saving agreement with Mossadegh, under which actual control and management of the organisation would remain with the AIOC. Truman sent Averell Harriman to Iran to convince Mossadegh of such a scheme. Arriving in Tehran on 15 July 1951, Harriman claimed that the United States accepted nationalization of the concession but insisted on having "a foreign-owned company to act as an agent of NIOC in conducting operations in Iran". Harriman's British counterpart, Lord Richard Stokes, signaled the UK also favored such an arrangement. Mossadegh however adamantly opposed the idea, believing it would only "revive the former AIOC in a new form." Mossadegh's opposition caused the British to conclude that he had to go. Officials at the Ministry of Fuel and Power wrote in September 1951: In October 1951, Mossadegh paid a visit to the United States, after the US embassy in Tehran had accidentally invited him (the invitation was actually meant for Churchill). There, in discussions with George C. McGhee, Mossadegh surprisingly agreed to a complex settlement, under which Iran would own the refinery in Kermanshah and administer the oilfields. The much larger Abadan Refinery was sold to a non-British company and the proceeds given to the AIOC as compensation. Further, the National Iranian Oil Company (NIOC) would sell an annual minimum of 30 million tons of crude oil to the AIOC for the next fifteen years. The board of the NIOC would consist of three Iranians and four foreigners and would conduct most of its transactions using in sterling. Mossadegh prolonged his visit on Washington's urging because the US administration believed that the incoming Conservative government of Winston Churchill would be agreeable to that deal. However, the deal was rejected by the British, who believed Mossadegh's downfall was imminent. Several