Using the terms of the Canal treaty which allowed the British and French to use military force in protection of the canal, an Anglo-French force would invade the canal area and subsequently invade Cairo. Israeli troops invaded Gaza and advanced toward the Sinai on 29 October. Accordingly, under the terms of the Canal Treaty, the British and French troops attacked the Canal Zone on 31 October using a combined force of air strikes, naval bombardment, and parachute drops. Large amphibious and infantry units were steaming from Cyprus and Algeria toward the canal for the final occupation and push into Cairo. Whilst the operation had all the elements necessary for surprise and legerdemain, it lacked quickness of speed given the relative strategic weakness which the British and French found themselves in the post-war period. For although the British and French still had substantial force projection capabilities and were the overwhelming military power in the region, both countries were heavily dependent on American support for their economies through the purchase of British and French debt, American direct investment, and most importantly, through the support American oil companies provided for European consumption. Consequently, by the time when the Anglo-French armada began its reinforcement of British and French positions on the Canal, the American government had already come under massive pressure from the United Nations, the Soviet Union, and most importantly from American oil companies which saw the British and French as impediments to their commercial expansion in the Middle East. When the American anger at the British and French intervention was felt at Whitehall, the British government fractured between those who saw the futility of maintaining the British Empire, those who saw the potential threat the Americans posed to the overall British economy should they end financial support of the British economy, and those British interests which still saw a need, a necessity and a reason for maintaining the British Empire. Thus, when the Eisenhower Administration initiated an oil embargo on the British and French, there was immediate panic in the British government. The French however were proving more resolute and flouted American demands stating matter of factly that America had no interest in the Middle East and were duplicitous in their support of Arab nationalism and anti-colonialism. However, with the embargo, the British pound which as a reserve currency was used in the purchase of oil had its liquidity threatened. While the British government debated this turn of events, the military campaign dithered and proved lacklustre in its execution, thereby buying crucial time for the Nasser regime to rally support from American liberals, the Soviet Union, and others in the United Nations. Finally, when in a bid of solidarity with the Nasser regime, the US government said it would no longer price support the British pound through the purchasing of British debt, the appeasers within the British government gained the upper hand and forced a surrender to American demands.