"We remain concerned by amassing of Chinese maritime militia vessels in the Union Bank area of the South China Sea and China’s efforts to impede the lawful rights of our treaty ally the Philippines," Kirby said during a briefing.

Kirby said that the Theodore Roosevelt carrier strike group along with the USS Makin Island Amphibious Readiness Group are undertaking training and operations in the South China Sea.

Media reports suggest that hundreds of Chinese boats are currently inside the Philippines’ 200-mile Exclusive Economic Zone(EEZ)at Whitsun Reef in the South China Sea. China claims that vessels are sheltering from bad weather and carry no militia aboard.

Kirby pointed out that the United States he is committed to the 1951 US-Philippine Mutual Defense Treaty.

"And certainly any attack on the Philippines would warrant us acting on those commitments. But we are just not there yet. Of course, no one wants to see this come to blows or to result in any conflict," he said.

China’s territorial and maritime claims in the South China Sea region overlap with those of several other nations. The United States has repeatedly voiced concern over the Chinese activities in the region and has sent military ships there to ensure freedom of navigation.