Dick Cheney, the US vice-president, warned on Monday that the withdrawal of US forces from Iraq would have disastrous consequences for American security, and said critics of the war were overlooking the substantial progress the nation had already made in fostering democracy and stability in the country.

The speech at the American Enterprise Institute in Washington was the latest in a series of efforts by the administration of President George W. Bush to shore up flagging public and congressional support for the war.