The Gulf War was a war waged by coalition forces from 35 nations led by the United States against Iraq in response to Iraq's invasion and annexation of Kuwait arising from oil pricing and production disputes. On 2 August 1990, the Iraqi Army invaded and occupied Kuwait, which was met with international condemnation and brought immediate economic sanctions against Iraq by members of the UN Security Council. UK prime minister Margaret Thatcher and US president George H. W. Bush deployed forces into Saudi Arabia, and urged other countries to send their own forces to the scene. An array of nations joined the coalition, forming the largest military alliance since World War II. Most of the coalition's military forces were from the US, with Saudi Arabia, the United Kingdom and Egypt as leading contributors, in that order. Kuwait and Saudi Arabia paid around US$32 billion of the US$60 billion cost.