A senior US Navy official advised Washington's allies to challenge what he called "aggressive behavior" by China following a reported incident involving China's coastguard and a Philippines vessel in the South China Sea.
Vice Admiral Karl Thomas, commander of the US Navy's Seventh Fleet, made the remarks to Reuters during a port call in Manila on Sunday.
Earlier this month, the Chinese coastguard reportedly blocked Philippine vessels carrying supplies to Filipino military personnel stationed on a grounded World War II warship, which Manila has intentionally grounded on a shoal in the South China Sea.
China claims sovereignty over almost the entire South China Sea, which overlaps with the waters of Malaysia, Vietnam, Brunei, Taiwan, and the Philippines. Beijing has repeatedly called for the Philippines to remove the warship -- which Manila uses as a makeshift military base -- and "restore it to its unoccupied state."
Using the alleged incident as an example, the American official said, "You have to challenge people I would say operating in a grey zone. When they're taking a little bit more and more and pushing you, you've got to push back, you have to sail and operate."
"There's really no better example of aggressive behavior than the activity on 5 August on the shoal," he alleged.
Thomas assured the Philippines of US backing in the face of "shared challenges" in the region, saying, "My forces are out here for a reason."
China has consistently opposed military activity by other countries in the strategic waterway, through which $5 trillion in goods are shipped yearly.
However, defying the Chinese warnings, Washington continually sent military vessels to the waters, prompting protests from Beijing.