Could China launch a preemptive series of air/missile strikes against U.S. bases/stockpile areas and slow America's ability to defend their regional interests...sure.
But that would only, IMO, be at best temporary.
You control the skies, you control the war. And China simply does not (not apparently will it by 2020) have the air power to take on the U.S. Air Force and Navy. Not even close. Heck, they would have a hard time taking out the Japanese 'air force' (which undoubtedly would be an active U.S. ally in any regional war).
It might take a few weeks (at most) for America to transfer enough air power to the region to gain air superiority, but it would happen. And once they control the skies, they can ship all the troops/equipment/supplies they need.
Sure, China could win the opening battle (like Japan did at Pearl Harbor in 1941) by a preemptive strike. But win the war in 2020...forget it.