The war of words is escalating again in the South China Sea, with the head of U.S. Pacific Command accusing China of creating "false sovereignty" through "aggressive, coercive" island-building in the disputed Spratly islands.

The stronger language comes as the United States weighs its next steps in the region.

In 18 months, China has reclaimed almost 3,000 acres of partly submerged reef to create land bases for military purposes, Adm. Harry Harris said recently at a security forum in Colorado.

The buildup includes ports deep enough for warships and a 10,000-foot runway, the online Defense One reported Harris as saying.

To the American public, the land reclamation might seem to be a minor matter, Harris said. But he added that actions by China to enforce its claims "could have far-reaching consequences for our security and economy by disrupting the international rules and norms that have supported the global community for decades."

He noted that $5.3 trillion in annual global trade relies on unimpeded sea lanes through the South China Sea.

U.S. Defense Secretary Ash Carter said in late May that he was "deeply concerned" about China’s island-building and potential for "miscalculation or conflict among claimant states."

In response to China’s activities, Adm. Scott Swift, the head of U.S. Pacific Fleet, flew in a P-8A Poseidon surveillance plane over the South China Sea July 18, raising the ire of China.

Ralph Cossa, president of the Pacific Forum Center for Strategic and International Studies in Honolulu, said his guess is that Carter’s "gotten the word that people think the Chinese are pushing us around, and we’re just sitting here taking it — and that’s because we’re preoccupied (elsewhere)."

"So I think the decision was made that we have to start making the Chinese a little nervous and we’ve got to start puffing up a little bit to make sure that people understand that hey, we really are serious about this," he said.

Steps like Swift’s fly-by are part of an orchestrated effort "to let the Chinese know that they’ve pushed a little too far and they’ve gotten our attention, and now we’re going to let them know it," he said.

The Spratly islands are claimed by China, Taiwan, Malaysia, Brunei, the Philippines and Vietnam. While several of those countries have also conducted land reclamation, the combined total is dwarfed by China’s "massive" buildup, Harris said.

China is "changing the status quo in the region through aggressive, coercive island-building without meaningful diplomatic efforts," Harris said.

China claims most of the South China Sea, and says it has the sovereign right to the buildup — which it maintains can offer humanitarian assistance, and does not affect freedom of navigation.

"Then they go on and talk about how the whole thing is theirs, and you need permission to go sail through (there) or fish," Cossa notes.

Cossa said he’s not worried about the United States and China coming to blows, but "the need to respond is rising."

He recommends resupplying a derelict Philippine navy ship that’s still manned but is aground on Second Thomas Shoal in the Spratlys southwest of Palawan.

The Philippines have been repairing the ship, with Beijing, in turn, calling Manila a "regional troublemaker."

"I think the U.S. should announce for humanitarian reasons we are providing resupply to our ally the Philippines," Cossa said.