Senior administration sources are confirming that President Bush is backing up his warnings to Iraq.
They said the president has approved tentative Pentagon plans for invading Iraq -- in case a new United Nations weapons inspection effort collapses.
The sources said the plan calls for an air, land and sea force of up to 250,000 troops.
They said initial plans to use 100,000 or fewer troops were scrapped in favor of the bigger force favored by General Tommy Franks, who would run any war in Iraq.
U.S. officials have promised "zero tolerance" if Saddam Hussein refuses to go along with a new UN Security Council resolution, which demands that he open up fully to inspectors.
Iraqi lawmakers are meeting to consider the resolution. They have until Friday to respond.