Lingering anger in Europe over the U.S. invasion of Iraq explains why some allies are reluctant to heed U.S. calls for more combat troops in Afghanistan, Defense Secretary Robert Gates said Friday. It was his first public acknowledgment of such a link to the Iraq war.

Gates said he would attempt in a speech here Sunday at an international security conference to decouple perceptions of the Iraq war, in which NATO has no fighting role, from views of Afghanistan, where NATO is in charge of the fighting but has fallen short on commanders' requests for more troops.

On a flight to Munich from Vilnius, Lithuania, where he attended two days of NATO talks dominated by Afghanistan, Gates associated Iraq with what lay behind Europe's general skepticism about fighting in Afghanistan.

"From our perspective, I worry that for many Europeans the missions in Iraq and Afghanistan are confused," he told reporters traveling with him, implicitly acknowledging a political cost of the Iraq invasion.

"I think they combine the two," he added. "Many of them I think have a problem with our involvement in Iraq and project that to Afghanistan and don't understand the very different — for them — very different kind of threat" posed by Al Qaeda in Afghanistan, as opposed to the militant group in Iraq that goes by the same name and is thought to be led by foreign terrorists linked to Al Qaeda.

Germany, which is hosting the Munich conference and which has refused Gates' explicit appeals to send combat forces to southern Afghanistan, and France were among the most vocal opponents of the Iraq invasion prior to the war. Britain has been the most supportive, and it has the second-largest number of troops in Afghanistan.

Despite earlier refusals, France now is considering sending troops to join the fight against the Taliban in southern Afghanistan after Canada's appeal for 1,000 extra forces to support its beleaguered force in volatile Kandahar province. French officials cautioned that it was unlikely Paris would provide all the troops Canada is seeking and said a decision was unlikely before April, when NATO leaders meet for a summit in Bucharest, Romania.

Such a move could ease tensions in NATO, where a rift has emerged between nations such as the United States, Canada and Britain who have troops in the south, and those like France, Germany and Italy whose units operates in the relative safety of north and west Afghanistan.

NATO, through its International Security Assistance Force, is in charge of the war, although the top commander is an American, Army Gen. Daniel McNeill, and the United States is the biggest provider of troops. Of the 42,000 total troops, about 14,000 are American, plus the United States has another 13,000 operating separately in eastern Afghanistan hunting terrorists and training Afghan forces.

Gates suggested that while not all Europeans see the various insurgent elements in Iraq as part of the international terror problem, they might be persuaded on the issue of Afghanistan, which was a refuge for Osama bin Laden's Al Qaeda network and a launching pad for the attacks of Sept. 11, 2001.

Gates has argued that if Afghanistan were allowed to fail, it could again become a haven for Al Qaeda and that Europe would be one its top targets.

"Our view, from the U.S. standpoint, is that Al Qaeda in Iraq is not just a problem for Iraq, but let's leave that aside," he said. "I want to focus on why Al Qaeda in Afghanistan and failure in Afghanistan would be a security problem for Europe."

As he has previously, Gates also made the point that some European allies have coalition governments with little political maneuvering room on such a sensitive topic as Afghanistan. He also praised those allied countries which have contributed combat troops as well as those helping in other ways.

He noted news reports that France might be willing to send combat troops into southern Afghanistan and he said this would be a welcome addition.

He said none of the allies made commitments to provide more troops in Afghanistan. Nonetheless, he said the discussions were cordial and that he was encouraged by what he described as an impression that some defense ministers are considering "what more they might be able to do" on the troop issue.

Gates said that parts of his speech on Sunday would be "directed at Europeans, not their governments, in an effort to try to explain why their security is tied to success in Afghanistan" and how the outcome in Afghanistan could affect the future of the NATO alliance, which originally was designed to protect Europe, the United States and Canada against a military threat by the former Soviet Union.

In congressional testimony on Wednesday, Gates expressed a fear that NATO could devolve into a "two-tiered alliance," with some member countries doing the fighting in NATO's name and others refusing.

"I remain concerned about that," Gates said in the in-flight interview. "I don't think we're there at this point. I'm not sure we're even really close. But I see it out there in the more distant future if ... these current conditions continue well into the future and get worse."

Gates was asked about the possibility that his direct appeal to Europeans on the issue of an Al Qaedathreat to their homelands might backfire.

"There always is a risk it will be counterproductive," he replied. "I am going to try and do this in a very measured way so that I don't come across as (saying), 'The sky is falling."'