(Bloomberg) -- A Philippine Navy personnel sustained “severe injury” after the China Coast Guard’s “intentional high-speed ramming” in the South China Sea on Monday, the Philippines’ military said.

The injured personnel has been safely evacuated and received medical treatment, military public affairs chief Colonel Xerxes Trinidad said in a statement Tuesday. He added that the China Coast Guard’s “aggressive behavior” is “unacceptable.”

The latest incident shows how maritime encounters between China and the Philippines have increasingly resulted in injuries. Beijing has maintained that its actions in contested waters are lawful.

GMA News earlier reported that a soldier had a finger cut off and several others were hurt during Monday’s encounter. China’s coast guard also seized high-powered firearms from Filipino troops and a Philippine rigid hull inflatable boat was punctured, the news outlet also said, citing an unnamed source.

The encounter happened after the Philippine military deployed six vessels from different entry points for a mission to resupply troops at its outpost in Second Thomas Shoal in the disputed waters, GMA News said.

The China Coast Guard said on Monday that the Philippine supply ship “deliberately collided” with Chinese vessels and it took “control measures” such as warning and interception, boarding and inspection, and forced eviction against Philippine vessels “in accordance with the law.”

Philippine President Ferdinand Marcos Jr. said in the past months that he would invoke a mutual defense treaty with the US if a Filipino soldier dies from a foreign attack. At a top regional defense forum in May, Marcos said his nation will respond accordingly if a Philippine citizen is killed by a “willful act.“

The Southeast Asian nation’s longtime ally, the US, earlier condemned China’s “escalatory and irresponsible actions.” It also reaffirmed that Washington’s 1951 defense treaty with Manila extends to armed attacks on Philippine armed forces and coast guard anywhere in the South China Sea.

Other countries also stood by Manila. The Australian government said it is “deeply concerned by reports of the forcible boarding and towing of Philippine vessels and the seizure of equipment.”

“This is an escalation in a pattern of deeply concerning and destabilizing behaviour by China,” Australia’s Department of Foreign Affairs and Trade said in a statement.

--With assistance from Cliff Venzon.

(Updates with Philippine military statement and Australia’s comment.)

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