WASHINGTON - President George W. Bush said Monday the United States cares deeply about protecting innocent civilians in Afghanistan, but that it's difficult because Taliban insurgents are using them as human shields.

Bush, after meeting with NATO Secretary General Jaap de Hoop Scheffer at the president's Texas ranch, also pledged to work on allies to "convince them that they must share more of the burden and ... the risks'' in Afghanistan.

A sharp increase in violence there in the last several weeks, including more civilian deaths, is causing an uproar that's threatening the stability of the Afghan government and the deployment of foreign troops.    "Every innocent civilian fatality is one too many,'' said Hoop Scheffer, adding that it was also "unavoidable.''

"But look at the number of Afghan civilians killed by the Taliban and by our opposing forces,'' he said.

"We are not in the same moral category as our opponents. We don't behead people. We don't burn schools. We don't kill teachers. We don't plant roadside bombs. We don't send in suicide bombers.''

Canada has 2,500 soldiers in Afghanistan, mostly in the Taliban heartland in the south where many European countries won't serve.

"In order for NATO to be effective, it has to transform itself into an organization that actually meets the threats that free nations face,'' said Bush.

"Afghanistan is still one of the front lines in our fight against terrorism,'' added Hoop Scheffer. "It is my strong conviction that the front line should not become a fault line.

"That is why it's so important that all 26 NATO allies are committed to Afghanistan and that the whole international community, for the longer term, stays committed to that nation.''

About 1,600 people have been killed in insurgency-related violence this year, including hundreds of civilians, according to an Associated Press count based on U.S., NATO and Afghan officials.

Casualties mounted last week in revenge suicide bombings after the Taliban's most senior military leader was killed.

 "We can no longer accept these (civilian) casualties,'' President Hamid Karzai told NATO earlier this month.

"The Afghan nation has the right to complain.''

The Afghan parliament recently called for a ceasefire and negotiations with insurgent groups, saying too many civilians are getting caught in the crossfire, particularly during air strikes.

U.S. General John Craddock, NATO's top military commander in Afghanistan, said last week officials are reviewing how troops apply "rules of engagement'' or the circumstances where they start shooting.

"We still have very much the hearts and minds of the Afghan people,'' Hoop Scheffer insisted.

"And we'll do everything we can to avoid civilian casualties.... We'll look very seriously into that.''

Bush also emphasized the long-term strategy to rebuild Afghanistan and strengthen democratic institutions.

Besides Afghanistan, the two men talked about NATO expansion, the organization's role in the Serbian province of Kosovo, and missile defence.

The U.S. is trying to reassure Russian President Vladimir Putin that the system to destroy incoming ballistic missiles, including plans to install radar and interceptors in Eastern Europe, wouldn't threaten him.