The decision by the Obama administration to arm select Syrian rebel groups marks a tipping point in the U.S. involvement in the country's 27-month long civil war. Partly in response to new evidence of chemical weapons use by the Assad regime -- a U.S. "red line" -- the United States is now rapidly moving to provide small arms, ammunition, and possibly mortars and antitank rockets to the rebels -- but for now holding the line short of antiaircraft missiles.

The Department of Defense faces a stark budgetary choice that will profoundly affect the future of the U.S. military. During past drawdowns, DOD chose to save money by cutting force structure, readiness, and modernization, while retaining the fundamental ways in which it does business. This time, however, skyrocketing internal costs are consuming so much of the defense budget that this path would require even deeper cuts to military capabilities. The resulting military would be much smaller and far less capable, and would almost certainly require the United States to change its long-standing global strategy.

I'm glad to see a concerned senior Army officer respond to my recent piece on the risks of brain drain inside the U.S. military. Lt. Gen. Ben Hodges undoubtedly speaks for many senior leaders in each service who feel exactly the same way about this looming challenge: "Hey, we don't even have a problem!"

The wars of the 21st century will be dominated by three overlapping types of conflict: Wars of Silicon, Wars of Iron, and Wars in the Shadows. The United States must design a new readiness and investment strategy in order to effectively deal with all three. Yet today it continues to pour scarce resources chiefly into its sphere of long-held dominance -- Wars of Iron. This is a potentially disastrous mistake, but one that can be corrected if we act now.

In his recent book Bleeding Talent, Tim Kane joins a growing chorus of serving and former junior officers to deliver a wake-up call to today's military leadership in the face of a major drawdown. Their message: If you ignore the expectations of today's young, combat-experienced leaders as you shrink the force, your most talented officers and sergeants will exit, stage left.