Defense Secretary Chuck Hagel was unusually candid on his farewell tour of several U.S. military bases, sharing his views on when America should intervene militarily abroad.

At Fort Bliss on Thursday he cautioned against what he called Americans' tendency to think they can solve all problems and to decide, "Let's go to war ... let's commit troops."

Earlier, at an air base in Missouri, he said the people of the Middle East need to sort out their own conflicts.

"We can't fight those wars for those people," he said.

Under President Barack Obama, Hagel had to commit thousands of advisers and trainers to help the Iraqi security forces fight back an onslaught from the Islamic State militants and train Syrian rebels. He resigned in November under White House pressure.