WASHINGTON Vice President Dick Cheney has presented the administration's most forceful and comprehensive rationale yet for attacking Iraq, warning that Saddam Hussein would "fairly soon" have nuclear weapons. Cheney said that a nuclear-armed Saddam would "seek domination of the entire Middle East, take control of a great portion of the world's energy supplies, directly threaten America's friends throughout the region, and subject the United States or any other nation to nuclear blackmail." .The vice president's remarks, to a convention of war veterans Monday in Nashville, Tennessee, came as White House advisers said they were increasingly concerned about news accounts and the growing debate in Congress and among former high-ranking foreign policy officials over plans for Iraq. .Cheney's speech appeared intended to quell the confusion and present the administration as united behind the central idea that Saddam must be removed, sooner rather than later. ."What he wants is time, and more time, to husband his resources to invest in his ongoing chemical and biological weapons program, and to gain possession of nuclear weapons," Cheney said. .The risks of inaction, he said, "are far greater than the risk of action." .Administration officials said that Cheney's views mirrored those of President George W. Bush and were part of the continuing effort to convince the allies, Congress and the public of the need for what the administration has called "regime change" in Iraq. .The officials said that Bush was expected to focus on Iraq in a speech to the United Nations General Assembly on Sept. 12. They said the extent and nature of Bush's remarks were still under discussion. .Cheney also said it would be a useless - if not a dangerous - delay to seek a UN resolution requiring that Iraq submit to weapons inspectors, as the man who served as secretary of state for the first President Bush, James Baker 3d, argued in an opinion article in The New York Times on Sunday. ."Saddam has perfected the game of shoot and retreat and is very skilled in the art of denial and deception," Cheney said. "A return of inspectors would provide no assurance whatsoever." .The speech by Cheney was the most prominent of several steps taken Monday by the administration to build a public case for going to war against Iraq. At the State Department, officials said they would start a four-day program Tuesday to train 17 Iraqi expatriates in publicizing the brutality of Saddam's regime. .In Crawford, Texas, an administration spokesman confirmed that White House lawyers had concluded that the administration did not need congressional approval to attack Iraq. The spokesman, Ari Fleischer, asserted that previous congressional resolutions, as well as the president's power as commander-in-chief, already gave him that authority. .Republicans said that Cheney's speech, scheduled since early August, had been intended to lay out the most serious and complete case for an attack on Iraq. .The speech appeared designed in particular to answer critics who say that the administration lacks intelligence on Iraq's nuclear capabilities. .While Cheney argued that the administration could never know with precision the extent and type of Saddam's programs to develop weapons of mass destruction, he said it would be perilous to underestimate "a dictator who has already shown his willingness to use such weapons." ."There is no doubt that Saddam Hussein now has weapons of mass destruction," Cheney said. "There is no doubt that he is amassing them to use against our friends, against our allies and against us." .He cited as his sources Iraqi defectors, among them Saddam's son-in-law, Major General Hussein Kamel, who, Cheney said, "was subsequently murdered at Saddam's direction." Kamel defected in 1995, was debriefed by the CIA, returned to Iraq the following year and was then killed in a gun battle by family members. .Cheney concluded that Saddam's threat made preemptive action against Iraq imperative, noting that former Secretary of State Henry Kissinger had made the same argument in a recent opinion article in The Washington Post. Cheney also appeared to attempt to counter those who have cautioned against war with Iraq, like Brent Scowcroft, the national security adviser to the first President Bush. Republicans who favor war with Iraq welcomed Cheney's speech, calling it a direct and clear-headed opening shot in a public relations campaign that many said had seemed to veer out of White House control for much of August. ."When Cheney talks, it's Bush," said William Kristol, the editor of The Weekly Standard and a hard-liner on Iraq. "I think the debate in the administration is over - and this is the beginning of the serious public campaign." .But other Republicans who caution against war with Iraq said that Cheney's speech was another confusing signal from an administration whose debate over going to war has been uncharacteristically public. ."You've got the vice president making this detailed speech about why we should go to war," said Senator Chuck Hagel, Republican of Nebraska, who has been a frequent critic of the administration's plans for Iraq. "The president is not saying anything." .The administration's message is confusing, Hagel said, adding that if the president wanted to go to war, "then he is going to have to step forward himself and make the case." .