WASHINGTON — It’s up to Vice President Joe Biden to show that the U.S. effort to realign its gaze toward Asia hasn’t fizzled out.

Biden will arrive Monday in Tokyo on a weeklong trip to Asia, which is watching carefully to see how committed the Obama administration is to increasing America’s influence in the region as a hedge against an increasingly assertive China.

In meetings with leaders in Japan, China and South Korea, the vice president will seek to show that while the administration has been preoccupied with Mideast flare-ups and a series of domestic distractions, the U.S. remained determined to be a Pacific power.

At the same time, disputes among Asian nations seem to be boiling over, threatening instability in a region that’s vital to the U.S. economy.

American allies Japan and South Korea are barely speaking. China is butting heads with its neighbors and with the U.S. about Beijing’s new air defense zone over a group of tiny islands that have exacerbated long-simmering territorial conflicts.

The U.S. on Friday advised American carriers to comply with China’s demand that it be told of any flights passing through that defense zone.

Early in his presidency, Obama declared the U.S. was “all in” when it came to the Asia-Pacific.

His administration pledged to increase its influence, resources and diplomatic outreach in the region, and to bolster the U.S. military footprint so that by 2020, 60 percent of the Navy’s warships would be based there, compared with 50 percent now.