Bishkek, Kyrgyzstan ? In a pep talk Friday to U.S. troops in this Central Asian outpost, Defense Secretary Donald H. Rumsfeld urged them to prepare for a long war against the “evil of mass murderers” and not only in Afghanistan.

“To the extent that they have safe havens, sanctuaries where they can go, then the effort we’ve put into Afghanistan will be for nothing,” he told about 400 troops assembled under a tent.

About 1,000 U.S. troops are based in Bishkek for fighter, cargo and air refueling missions over Afghanistan.

Rumsfeld’s four-nation Central Asia tour is taking him next to Afghanistan for meetings with officials of the interim government and visits to U.S. and allied troops.

In a sign of security concerns, reporters accompanying Rumsfeld were forbidden to report in advance which parts of Afghanistan he would visit. The last time he was in Afghanistan the Taliban regime had just been defeated, the interim government headed by Hamid Karzai had not yet been installed and speculation about Osama bin Laden’s whereabouts was rampant.

Rumsfeld rarely mentions bin Laden in public, but he was reminded Friday that at least some of those in uniform equate success in Afghanistan with getting rid of bin Laden.

In a question-and-answer session with U.S. and allied troops, one airman asked: “When we get our hands on Mr. bin Laden, are we going to negotiate with him or annihilate him?”

Grinning amid hoots and hollers from his audience, Rumsfeld replied, “In truth, it’s kind of his choice.”