China claims most of the South China Sea, through which $5 trillion in trade passes every year. The Philippines, Vietnam, Malaysia, Taiwan and Brunei have overlapping territorial claims.
Last week, US Secretary of State John Kerry told a meeting of regional leaders in Kuala Lumpur, Malaysia, that China's construction of facilities on man-made islands for "military purposes" was raising tension and risked "militarization" by other nations in the region.
Kerry also criticized "restrictions" put in place in recent months by China, saying the United States would not accept any such restrictions on freedom of navigation and overflights.
The Chinese Foreign Ministry hit back at Kerry’s accusations on Monday, saying in a statement to Reuters that Beijing sees freedom of navigation in the region as key because it is an important conduit for trade and natural resources.
That freedom, however, does not extend to the ships and aircraft of foreign militaries, the Ministry added.
Philippine military officials have accused China of repeatedly warning Philippine aircraft away from the artificial islands in the Spratly archipelago of the South China Sea.
The Chinese navy also issued eight warnings to the crew of a US surveillance plane that was conducting overflights in the area in May, according to CNN, which was aboard the US aircraft.
China has rejected calls to end to its reclamation projects in the region, and defiantly announced that it would continue to build facilities on the man-made islands.
The Foreign Ministry said China is building civilian facilities on the Spratly Islands for the "public good," including hospitals, maritime research institutes, lighthouses and search and rescue facilities.
A Philippine lawmaker told Reuters on Monday he had information that a Chinese coast guard ship dropped anchor more than a month ago near a rusting Philippine Navy transport ship in the disputed Second Thomas Shoal.
"I think China has no intention of leaving the area and they are waiting for our ship to collapse or prevent us from reinforcing that ship," Congressman Francisco Acedillo, a former air force pilot, said at a naval base in Manila.
Acedillo said the presence of a Chinese ship within Second Thomas Shoal was a serious threat to the Philippines, Reuters reported.