Story highlights The Naval pilot-turned-politician survived over five years as a prisoner of war in Vietnam

McCain asked the Pentagon for more information on the current and future fight against ISIS

Washington (CNN) Sen. John McCain warned Tuesday that the Obama administration's "grudging incrementalism" in the fight against ISIS risks a failure akin to the Vietnam War.

"As a young military officer, I bore witness to the failed policy of gradual escalation that ultimately led to our nation's defeat in the Vietnam War," McCain, chairman of the Senate Armed Services Committee, wrote in a letter sent to Defense Secretary Ash Carter.

The Naval pilot-turned-politician survived over five years as a prisoner of war in Vietnam.

McCain said that he fears the nation's current strategy of "grudging incrementalism in the war against the Islamic State risks another slow, grinding failure for our nation."

In the letter, the Arizona Republican asserted that conversations he has had with military commanders confirm for him that the military's actions have shifted from "considering what it will take to win" to "what they will be allowed to do by the administration."

Read More