Though the defense department refuses to acknowledge publicly that troops in the region are being readied for an invasion, soldiers and military gear have been flooding in to neighboring states for weeks.

But now the strategists are rethinking their plans. They need to avoid tying up tens of thousands of US troops while they wait for the completion of a weapons inspections process in Iraq, which - even after an agreement is reached at the UN - could last more than three months.

"It's fair to say that there's some recalibration going on," the Washington Post quoted one senior defense official as saying.

Russia, France and China remain implacable in their opposition to a redrafted US resolution that threatens Saddam Hussein with "serious consequences" if he resists UN weapons inspections and twice accuses him of being in "material breach" of earlier resolutions - language which they say implicitly authorizes George Bush to use military force without returning to the security council.

Igor Ivanov, the Russian foreign minister, told reporters in Moscow that "the American draft resolution does not answer the criteria which the Russian side laid out earlier and which it confirms today."

The UN delay, when added to the estimated 105-day period that the inspectors would need to do their work and report, threatens to frustrate the Pentagon's preference for a January invasion.

But the biggest disadvantage to fighting a war in late spring or summer - Iraq's soaring temperatures - may be less of a problem than anticipated, due to technological advances.

"We would prefer to fight in the winter, but the weather is not necessarily a show-stopper," said Michael Vickers of the Washington thinktank the Center for Strategic and Budgetary Assessments.

The suits that troops would have to wear to protect themselves from potential chemical weapons attacks are better ventilated and far less bulky than they were, Mr Vickers said.

Where heat seeking missiles sometimes went off course in temperatures of up to 49C (120F) during the last war, the army says new guidance systems allow missiles to find their target even through thick summer clouds.

"The US military is trained to fight in all weather conditions, day or night," said a Pentagon spokesman, Lieutenant Dan Hetlage.

A different concern for the military, however, may come in the form of a congressional report claiming that trained pilots and crew in two of the US army's reserve forces - the air national guard and the air force reserve - are leaving in droves to avoid taking the Pentagon's anthrax vaccine whose side-effects include nausea, diarrhea, vomiting and, in rare cases, hallucination, depression or delirium.