Biden gave a pep talk to the aircraft carrier’s crew, stressing the importance of their role in maintaining law of the sea navigation rights.

In October 2015, the U.S. began freedom of navigation operations in the South China Sea, sending warships, including the aircraft carrier, within the 12-mile territorial zone of artificial islands China has been building up into military outposts. The mission is aimed at preventing China from sealing the disputed area for operations of its nuclear-powered submarines.

The subs carry nuclear-armed ballistic missiles that have a range of 8,000km. The U.S. cannot afford to sit still and watch Chinese nuclear submarines freely expand the scope of their operations from the South China Sea to the Pacific, putting the U.S. mainland within range of their missiles.

U.S. President Barack Obama, who was keen to expand cooperation with China over global warming and other common challenges, was initially reluctant to approve the freedom of navigation operations.

“As the two largest economies in the world, we have a special responsibility to lead the way in ensuring sustained and balanced growth not only here in Asia but globally,” Obama once said, recognizing the importance of China-U.S. ties.

http://asia.nikkei.com/Politics-Economy/International-Relations/South-China-Sea-issue-awaits-next-US-president?page=1