President Barack Obama has told U.S. troops he will not send them into conflict without adequate support. The president spoke to a military audience in the state of Alaska Thursday while heading to Asia.

He made a commitment to the nation's service members, in a refueling stop at Elmendorf Air Force Base on his way to visiting four nations in Asia. "I want you guys to understand I will never hesitate to use force to protect the American people or our vital interests.  I also make you this promise: I will not risk your lives unless it is necessary to America's vital interests," he said.

The president and his top advisers have been discussing how to proceed with the war in Afghanistan.  Mr. Obama told the troops and their families any plan he chooses will include sufficient support for them. "We will give you the strategy and the clear mission you deserve.  We will give you the equipment and support that you need to get the job done, and that includes public support back home.  That is a promise that I make to you," he said.

The president did not specifically mention Afghanistan in his talk to the troops, but he is expected to send thousands more service members to fight there.  After meeting with his advisers on Wednesday, Mr. Obama asked for revised options.

White House press secretary Robert Gibbs says the president will not announce his Afghanistan strategy before returning from Asia next week.  Gibbs also says Mr. Obama wants benchmarks for evaluating U.S. progress in Afghanistan, and will not commit to an open-ended conflict.

Public support for increasing troop levels in Afghanistan has been eroding.  An Associated Press poll this week shows that 54 percent of Americans oppose sending more troops, up from 50 percent in October.

The president's Asia trip will take him to Japan,Singapore, China and South Korea.  The global economy, trade, climate change and North Korea's nuclear program are expected to be among the topics covered in the various meetings.