U.S. forces in Afghanistan are facing unexpected resistance from the remnants of the Taliban and Al Qaeda, the chairman of the Joint Chiefs of Staff said Tuesday.

Troops have found weapons, medical equipment and high quality supplies as they seek out the pockets of resistance, Gen. Richard B. Myers said.

"Afghanistan is still a very dangerous place," Myers said at a news conference preceding a speech to the Economic Club of Detroit. "It would be dangerous to underestimate how organized they (Taliban and Al Qaeda) are."

The American military presence in Afghanistan will remain at current levels for at least several more months, Myers said.

He said he did not know whether Usama bin Laden was dead following months of U.S.-led attacks in Afghanistan.

"My feeling is that he's probably still alive and still in the region," Myers said, adding "the effort has never been against bin Laden.

"The effort has been against the Al Qaeda organization."

Myers said the military was prepared to carry out any mission of any size requested of it by President Bush.

Myers said 971 National Guard members in 22 units from Michigan have been called up as part of Operation Enduring Freedom.

"The first thing you can do is be patient," Myers said during a question-and-answer period during his speech. "This is going to take time. This is going to take years."

He declined to answer questions about the fighting in the Middle East and Secretary of State Colin Powell's mission there.

Defense Secretary Donald H. Rumsfeld said at a Pentagon news briefing Monday that the U.S. military hasn't tracked down bin Laden during its six-month war in Afghanistan, but it has made it harder for his Al Qaeda terrorist network to operate — and that's better than nothing.

U.S. officials say there has been little or no sign of bin Laden since last December. There is speculation that he escaped into Pakistan or another country; that he remains in Afghanistan; or that he is dead.

Rumsfeld said U.S. forces are focusing on cave complexes and other former Al Qaeda hide-outs and fortifications in eastern Afghanistan. The troops are scouring these areas for clues to terrorist plans.