The United States held their first joint naval and air exercises with Japan, Australia and the Philippines in the South China Sea on Sunday – the same day China’s military announced its own exercises in the disputed sea.

The four countries said they will hold joint maritime cooperative activities in the Philippines’ exclusive economic zone to safeguard “the rule of law that is the foundation for a peaceful and stable Indo-Pacific region.”

They will also uphold “the right to freedom of navigation and overflight,” according to a joint statement issued by their defense chiefs on Saturday.

In response to the joint naval exercises, China’s military said on Sunday that it had conducted air and sea patrols and that all military activities that “disrupt the South China Sea and create hotspots” are under control.

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China did not give specific details about its own military activities, nor did it mention the United States or the joint exercises in its statement.

Likewise, the US and its allies did not mention China in their joint statement.

But the four countries reaffirmed their stance that a 2016 international arbitration ruling, which invalidated China’s expansive claims on historical grounds, was a “final and legally binding decision.”

China has refused to participate in the arbitration, rejected the ruling and continues to defy it.

The Philippines brought its disputes with China to international arbitration in 2013 after a tense sea standoff.

These growing tensions in the disputed waters come a few days before US President Joe Biden is set to host Japanese Prime Minister Kishida Fumio and Phillippine President Ferniand Marcos Jr. in a trilateral summit at the White House on April 11.