The brilliant blue waters, thick foliage and bucolic atmosphere on this seemingly idyllic archipelago deep in the Pacific Ocean belie the key role it now plays in a titanic geopolitical struggle.

Palau, where brutal World War II clashes once unfolded, is again on the frontline as China and the United States and its allies prepare their forces in an intensifying contest for control over the Asia-Pacific region.

The democratic island nation of just 17,000 people hosts American-controlled airstrips and soon-to-be-completed radar installations that the U.S. military describes as "critical” to monitoring vast swathes of water and airspace. It is also a key piece of the Second Island Chain, a string of strategically located islets that America is fortifying in an effort to deny China access to the Western Pacific.