"Should U.S. worry about China's island building?"

James Kraska on CNN: Should U.S. worry about China's island building?

Short answer: Yes!

Meanwhile, over the past six weeks, Philippine and U.S. maritime patrol aircraft have been warned away from the artificial island, as though China is claiming that its work generates a territorial sea and national airspace. U.S. Navy Adm. Harry Harris has dismissed these maritime claims as "preposterous," while Defense Secretary Ash Carter has stated that the United States will "fly, sail, and operate wherever international law allows."

The "United States and everyone else in the region has a stake in this" because "it gets to the question of freedom of navigation, freedom of the seas, freedom from coercion, abiding by peaceful and lawful processes," Carter told the media on his way to Singapore for the Shangri-La Dialogue security conference. "[A]nd that is...a longstanding U.S. position, as is freedom of flying, freedom to sail."

International law appears to support U.S. officials' skepticism about China's seeming territorial aspirations.

Under article 121 of the U.N. Convention on the Law of the Sea (UNCLOS), only "naturally formed" islands or rocks that are above water at high tide generate a 12-nautical mile territorial sea -- there is no lawful claim of sovereignty over a submerged reef or artificial island. Despite this, on April 24, China flashed powerful lights at Philippine aircraft near Subi reef and reportedly warned it to leave Chinese "territory."

Read the whole thing.

Nice power play, you've got there China. But a little ham-handed.