"It's the global striking power of America's armed forces that must deter or thwart the ambitions of aggressors," McCain, the Chairman of the powerful Senate Armed Services Committee, said.
"Too many have forgotten that our world order is not self-sustaining. Too many have forgotten that while the threats we face may not have purely military solutions, they all have military dimensions. In short, too many have forgotten that hard power matters," he said.
Even at odds with the president-elect Donald Trump, McCain has supported James "Mad Dog" Mattis as nominee for Defence Secretary.
The Senator pointed to threats posed by "violent Islamic extremism" across Middle East, Africa, Asia, Europe. "It should now be clear that we will be engaged in a global conflict of varying scope and intensity for the foreseeable future. Believing otherwise is wishful thinking," he said.
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The central challenge in the Middle East is not the IS, he said, but a breakdown of regional order "in which nearly every state is a battlefield for conflict, a combatant or both".
shifting the balance of power in Asia", North Korea, which is developing an missile capable of striking the US, and Russia, which has embarked on an expansionist agenda while leaving behind "a trail of death and destruction" in Syria.
A week before the take over of the next president, McCain said the United States must build a position of significant strength vis-a-vis Russia and any other adversary that seeks to undermine the country's national interests and challenge the world order. "We must reestablish deterrence and that is primarily the job of the Department of Defence," he said.
"What makes all of this worse is that America's military technological advantage is eroding. Our competitors, especially China and Russia, have gone to school on the American way of war and they are rapidly modernising their militaries to exploit our vulnerabilities with advanced anti-access and aerial denial capabilities," he said.
The Senator said all these problems have been compounded by caps on defence spending.