When assessing military risks, U.S. Navy Adm. Mike Mullen said he constantly assesses the readiness of combat troops in Iraq and Afghanistan.

"It impacts overall readiness, equipment readiness and people," Mullen said in a Department of Defense news release.

He is on a six-day tour to California, Hawaii and Australia.

Besides evaluating military on the ground, Mullen said he discusses readiness with service chiefs, who "have expressed concerns -- which I share -- about full-spectrum training and that we need to broaden the capabilities for which we are training right now."

The Joint Chiefs chair said his assessment considers the level of U.S. troop readiness against possible contingencies. When major operations in Iraq and Afghanistan end, Mullen said, the Middle East and central Asia will remain unstable.

He said even if he were "to magically wave a wand and get everybody back from Iraq and Afghanistan" it would still "take a while to reset" -- or replace equipment, enhance training, and give the troops a rest.