France, Russia, and Germany continued to press for further weapons inspections. The United States and Britain abandoned efforts to seek an explicit Security Council mandate for toppling Saddam Hussein and launched a war the following month.
But Powell's 5 February address -- considered the best case Washington could make to go to war -- is now part of the puzzling postmortem on suspected U.S. intelligence failures.
From the outset of his address last year, Powell asserted that the United States had considerable evidence of Iraqi misdeeds: "What you will see is an accumulation of facts and disturbing behavior. The facts and Iraq's behavior demonstrate that Saddam Hussein and his regime have made no effort -- no effort -- to disarm as required by the international community. Indeed, the facts and Iraq's behavior show that Saddam Hussein and his regime are concealing their efforts to produce more weapons of mass destruction."
Powell went on to point to developments in Iraq's nuclear, chemical, biological, and ballistic missiles programs.
He said Iraq had stockpiled enough chemical weapons agent to fill 16,000 battlefield rockets. Iraq had the capability to produce biological weapons, Powell said, with the ability to cause "massive death and destruction."
Iraq was also trying to acquire aluminum tubes, which Powell said were likely intended for use in centrifuges to enrich uranium. That would provide a way to make fissile material needed to manufacture a bomb.
But since Powell's report, U.S.-led teams have uncovered no major evidence of stockpiles of chemical and biological weapons. Unmanned airborne vehicles, which Powell warned could be used to spray biological agents, have been found to be unequipped to spread toxins.
The International Atomic Energy Agency has discounted the aluminum tubes and found Iraq did not have a viable nuclear program.
One area validated was Powell's charge that Iraq was seeking to build missiles capable of reaching beyond the 150-kilometer limit set by the United Nations. UN inspectors discovered missiles that exceeded the limit and were destroying them shortly before the war began last March.
But much of Powell's speech can now be dismissed, says Joseph Cirincione, director of the Nonproliferation Project at the Carnegie Endowment for International Peace. A study last month by the Carnegie Endowment concluded that Iraq was not an immediate threat to the U.S. or the Middle East and that the Bush administration had "systematically misrepresented" the danger from Baghdad.
"It's difficult to find a sentence [of Powell's report] that is actually accurate at this point," he said. "The secretary raises some 29 major allegations about the programs. As far as we know, none of those has been verified, and many of those are now almost certainly not true."
Cirincione says it is vital for senior Bush administration officials to correct the statements they made about Iraq to re-establish some credibility.
Powell told "The Washington Post" this week that he does not know whether he would have recommended an invasion of Iraq had he been told there was no evidence of stockpiles of banned weapons there. But he said the U.S. still did the right thing in toppling Hussein. And both the U.S. and Britain have announced plans to investigate Iraqi intelligence failures.
A former Canadian diplomat at the UN, David Malone, says Powell's international stature has suffered in the year since his report. Malone, who heads the International Peace Academy, tells RFE/RL that Washington's foreign-policy community must seek to avoid such apparent intelligence letdowns in the future.
"Intelligence remains important to key governments," he said. "The critical question mark over intelligence is whether it can remain uncontaminated by political agendas, which clearly over the past two years on the question of Iraq have had much more importance than they should have had."
What complicated the case of Iraq was Hussein's unwillingness to fully divulge information on his weapons program, although his regime repeatedly said it had disarmed. Throughout the prewar debate, chief UN monitor Hans Blix, who favored a continuation of inspections, often referred to Iraq's refusal to account for missing stocks of chemical and biological weapons.
The UN maintained an ominous list of unresolved biological and chemical-weapons issues, dating back to the end of the first Gulf War. Spokesman Ewen Buchanan of the UN Monitoring, Inspection, and Verification Commission (UNMOVIC) noted the problem in an interview with RFE/RL.
"We had been unable to account for everything which Iraq had admitted to having had in the past," he said. "By way of example, Iraq produced -- by their own account -- 8.5 tons of the biological weapon agent anthrax. They claimed they had destroyed this secretly in the summer of 1991, but the problem for us was how to verify whether that was true. They claimed to have poured it out on the ground years and years ago, but it was impossible for us to determine how much anthrax was there in the ground."
For some states, Hussein's pattern of noncompliance persuaded them that the tough U.S. approach was the right one. Following Powell's presentation last year, a group known as the Vilnius 10 issued a joint statement at the UN, saying its members were prepared to contribute to an international coalition in Iraq if it failed to comply with inspections.
The group comprised former communist states poised to become NATO candidates. They included Bulgaria, one of only four countries on the Security Council to openly side with Washington.
Romanian Foreign Minister Mircea Geoana, whose country also signed the statement, maintains that ousting Hussein was the right approach, regardless of the debate over weapons of mass destruction. He told a news conference earlier this week in New York that Romanians saw the overthrow of Hussein as a moral issue: "In Romania, the discussion about weapons of mass destruction was a secondary debate to the democracy debate. Of course, this was not the main topic of last year's discussion, including in the UN with the presentation of intelligence and whatever they presented. But for us, it was more of a moral democracy case than a weapons of mass destruction case."
Romania has contributed more than 800 soldiers to the coalition force in Iraq. Last month, it replaced Bulgaria on the Security Council and will preside over the Security Council just after the scheduled handover of power to Iraqi authorities on 1 July.
The Security Council this year is also due to debate the future of UNMOVIC. One suggestion favored by some members is to transform the agency into a permanent inspection corps at the UN to monitor chemical, biological, and ballistic missile programs.
(RFE/RL's Yuri Zhigalkin contributed to this report.)