The war in Afghanistan will be “much tougher than Iraq” regarding efforts to achieve peace and security, U.S. President Barack Obama’s special envoy to Afghanistan and Pakistan has told an international security conference.

"It's going to be a long, difficult struggle," Richard Holbrooke said at the Munich Security Conference on Sunday.

"In my view, it's going to be much tougher than Iraq," he said. "I have never seen anything like the mess we have inherited."

"We cannot afford failure in Afghanistan," Gen. James Jones, Obama's national security adviser, told leaders gathered in Munich.

"That's why the Obama administration will work closely with NATO and with the Afghan and Pakistani governments to forge a new, comprehensive strategy to meet achievable goals. This will be a shared effort with our allies. Afghanistan is not simply an American problem. It is an international problem," he said.

In an effort to strike at a key income source for Taliban militants, the top NATO commander said Sunday that operations to attack drug lords and labs in Afghanistan will begin within the "next several days."

Gen. John Craddock, who also heads the U.S. European Command, also said that the U.S. and its allies are making progress in their efforts to fill the need for more troops, equipment and intelligence-gathering in Afghanistan.

He would not disclose any specific commitments he received this weekend at the security conference.

NATO defence ministers at the conference differed on whether the focus in Afghanistan should be military or civilian.

The new U.S. administration plans to double the number of American troops in the country to about 60,000 in the next 18 months.

Canada has about 2,500 soldiers in Afghanistan, mostly based in the south around Kandahar. The military mission is slated to end in 2011.

NATO currently has about 55,000 troops in Afghanistan, almost half of them from the United States.

Germany has balked at sending more soldiers, saying reconstruction should be the focus.

German Defence Minister Franz Josef Jung said Sunday that more efforts should be paid to enhance security and reconstruction in Afghanistan amid calls from the United States to its allies to contribute more in the military aspect.

"I think it is absolutely necessary that we should implement the [security and reconstruction] process in Afghanistan even more effectively. There can be no development without security, but there can be no security without development, either," Jung told the conference.

"We will not win by military means alone," he said.