The American vice-president, Dick Cheney added his voice to the calls for pre-emptive military action against Saddam Hussein yesterday, arguing that the US could not afford to wait until Baghdad had a nuclear weapon.

His fiercely worded speech to war veterans in Tennessee was all the more significant because Mr Cheney speaks directly for the White House, which has been silent on Iraq policy in recent weeks.

"What we must not do in the face of a mortal threat is to give in to wishful thinking or wilful blindness," he said.

"We will not simply look away, hope for the best and leave the matter for some future administration to resolve."

Last week Mr Bush and his defense secretary, Donald Rumsfeld, criticized a media "frenzy" about Iraq, but leaks and hints have continued to flow from the White House and the Pentagon suggesting that the administration is still contemplating a war this winter.

Preparations are under way on other fronts. It was reported yesterday that President Bush's legal advisers have decided that he does not need to seek congressional approval to go to war with Iraq, because the mandate his father was given for the Gulf war 11 years ago is still in force.

The White House spokesman, Ari Fleischer, said yesterday that if it came to launching an attack on Iraq, Mr Bush "would consult with Congress, because Congress has an important role to play".

But he stopped short of saying that the president would seek formal approval.

It also emerged yesterday that 15,000 reservists, mainly in the air force and the air national guard, will be kept on active duty for up to two years, a year longer than usual and the longest tour of duty since the Vietnam war.

Mr Cheney, citing an argument put forward by the former secretary of state Henry Kissinger, said: "The imminence of [the] proliferation of weapons of mass destruction, the huge dangers it involves, the rejection of a viable inspection system, and the demonstrated hostility of Saddam Hussein combine to produce an imperative for pre-emptive action."

He rejected appeals to wait until the Iraqi leader was on the threshold of deploying a nuclear weapon. "If we did wait until that moment, Saddam would simply be emboldened and it would become even harder for us to gather friends and allies to oppose him," he said.

The speech, together with similar comments made recently by Mr Rumsfeld and the national security adviser, Condoleezza Rice, appeared to be part of a concerted administration effort to build up domestic and international support for a pre-emptive attack on Iraq.

It was a gesture of defiance in the face of the reservations voiced by some of the leading foreign policy authorities in the Republican party. At the weekend two secretaries of state under the president's father - James Baker and Lawrence Eagleburger - urged caution.

According to the Washington Post, one of the justifications for an attack on Iraq cited by Mr Bush's lawyers was the 1991 Gulf resolution in which Congress gave the first President Bush the authority to use military means to enforce UN security council resolutions, which include demands for President Saddam to eliminate Iraq's weapons of mass destruction.

The US argues that he has not done that.

The White House counsel, Alberto Gonzalez, also argued that the president's authority to go to war was inherent in his office of commander in chief, and the administration points to the resolution passed by Congress on September 14 last year authorizing the White House to respond militarily to the perpetrators of the September 11 attacks and any state harboring them.

All three arguments were criticized by constitutional lawyers in Washington yesterday. Herman Schwartz, a professor at American University, said the 1991 resolution "was never intended to cover something like this 11 years later. It gave the OK for what happened in Kuwait".

James Lindsay, an expert on constitutional issues in foreign affairs at the Brookings Institution, agreed that a reading of the 1991 vote to justify a war now "would take the resolution past its breaking point".

Prof Schwartz also argued that the title of commander of chief did not vest decision-making power in the president.

© Guardian Newspapers Limited 2002

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