Philippine President Rodrigo Duterte's recent calls for a "separation" from the United States and for U.S. troops to exit the Philippines within two years provide a series of wake up calls for Washington. As the American people prepare to choose their next commander-in-chief, a rethink of America's decades-old assumptions about Manila and the broader region are in order. Here's why.

Some Asian states have begun an inevitable balancing act between Washington and Beijing. China's rise and its increasingly aggressive behavior of asserting sovereignty over the South China Sea and unilateral imposition of its East China Sea air defense identification zone in recent years have demonstrated a determination to assert itself as the regional hegemon. Many in the area have taken notice and simply making their best of this geopolitical contest.

Duterte's comments over the past month are part and parcel of this trend as, it can be argued, were Thailand's and Malaysia's decisions to choose Beijing over Washington with their purchases of submarines and littoral mission ships last year and last week, respectively. Other states, such as India, Vietnam and Japan, have taken a different approach by strengthening their capabilities and solidifying their geopolitical relationships with Washington.