WASHINGTON (Reuters) - The new head of NATO will seek to ease American doubts about the alliance’s commitment to the Afghan conflict on Monday, even as European allies downplay chances of major reinforcements after eight years of war.

Anders Fogh Rasmussen, in his first major U.S. speech as secretary-general, acknowledges the need for more resources to fight the Taliban in the face of mounting Western casualties and fading public support, according to prepared remarks obtained by Reuters.

But the former prime minister of Denmark, who took over NATO’s top job last month, also criticizes those in the United States who belittle the contributions of allies.

Such behavior is counterproductive, he says, and may leave them “less inclined to make those efforts and those sacrifices” in the future.

“I’m a little concerned about the doubts I hear these days in the United States about NATO,” Rasmussen says in the speech to be delivered at the Atlantic Council in Washington at 5 p.m.

EDT (2100 GMT).

“Talking down the European and Canadian contributions -- as some in the United States do on occasion -- can become a self-fulfilling prophesy.”

His comments come on the same day as European defense ministers, meeting informally in Sweden, expressed reluctance to send a significant number of reinforcements.

“If you look at Europe, I don’t hear any voices saying we have an additional five or ten thousand soldiers to send to Afghanistan,” said Danish Defense Minister Soren Gade.

Opinion polls on both sides of the Atlantic show souring public sentiment over the eight-year-old conflict, which the top U.S. and NATO commander in Afghanistan, Stanley McChrystal, has warned likely will result in failure without more troops.

McChrystal is expected to seek 30,000 to 40,000 combat troops and trainers, according to defense and congressional officials.

European allies are not expected to offer any significant increase in trainers or troops unless the United States takes the lead.

But U.S. President Barack Obama, who is also working to reduce the U.S. military presence in Iraq, has said he will not decide on further reinforcements for Afghanistan until after a broad review of strategy.

Senator John Kerry, the influential chairman of the Senate Foreign Relations Committee, urged against committing more troops without clear goals or a timeframe.

“Otherwise, we risk bringing our troops home from a mission unachieved or poorly conceived,” Kerry said in an opinion piece in The Wall Street Journal published on Monday.

NOT RUNNING FROM FIGHT

Rasmussen was scheduled to meet Obama, Secretary of State Hillary Clinton and Defense Secretary Robert Gates on Monday and Tuesday, his office said.

SGT Justin Klock (L) and SGT Frank Iannacconne from the U.S. Army's Alpha Company, 3rd brigade of 10th Mountain Division based in Fort Drum, New York, take a position during a search for IED (improvised explosive device) laid by the Taliban in the village of Sha Mazar in Logar province September 26, 2009. REUTERS/Nikola Solic

In the speech, Rasmussen points to 9,000 additional non-U.S. troops who have joined the Afghan effort in the past 18 months, saying “the allies are not running from the fight, despite the conventional wisdom.”

The Netherlands and Canada already have set 2010 and 2011 withdrawal timelines. But Rasmussen says NATO “will stay for as long as it takes to succeed.”

He says more resources will be required and stresses the need to rapidly train Afghan forces so they can take the lead in providing security. He adds that “we have to do more now if we want to be able to do less later.”

“None of this will be quick and none of it will be easy,” Rasmussen says. “We will need to have patience. We will need more resources. And we will lose more young soldiers to the terrorist attacks of the Taliban.”

McChrystal’s leaked assessment included withering criticism of NATO’s International Security Assistance Force, saying that troops often lacked basic understanding of Afghan society.

Rasmussen says he is aware of frustrations in Washington, including restrictions some NATO nations put on their forces and delays in NATO decision-making.

“I am already working hard to address those very real problems,” he says in his remarks.

The Pentagon said on Monday any additional deployments would not happen until next year, even if Obama approved them immediately.

“There is a certain amount of train-up that is required to prepare for a particular battlespace and there is a certain amount of logistics in terms of moving equipment,” Pentagon spokesman Bryan Whitman said.