ABOARD USS CARL VINSON- Japan's navy on Saturday announced the start of a joint annual military exercise, with the Philippines observing the operations for the first time as the two countries seek closer maritime cooperation.

 F-35C stealth jet sits on deck of USS Carl Vinson in the Western Pacific.

The Japan-led Annualex exercise started on Friday with operations conducted by the naval forces of the United States, Australia and Canada, with the Philippines attending as an observer, Japan Maritime Self-Defence Force Vice Admiral Akira Saito told reporters.

"The Philippines is a very important country for us, and we are looking to coordinate with their navy at every possible opportunity," Saito said aboard the USS Carl Vinson as it sailed in an undisclosed location in the Pacific Ocean.

The exercise comes as Japan, the U.S. and the Philippines seek closer ties and deeper security cooperation to counter China, though Saito said the operations are not being conducted to target a specific country.

Last week, Japan said it would provide radar systems to the Philippines to bolster its security. The two countries also announced the start of negotiations for a reciprocal military access agreement.

"The more that our navies work together, the more multilateral our operations and our exercises are, the greater the security for this region. So I'm thrilled that Japan invited the Philippines to observe this year," Vice Admiral of the U.S. Seventh Fleet Karl Thomas said.

Saito added that strong cooperation between like-minded countries is crucial for the stability of the Indo-Pacific region.

The operations will be conducted for 10 days and will involve 30 ships and 40 aircraft, Saito said.

There has been a string of clashes between the Philippines and China in recent weeks, including a collision in October, while Japanese and Chinese ships also faced off in the East China Sea last month.

Separately the Philippines' coast guard said on Saturday it would maintain its regular supply missions to troops stationed on a disputed atoll in the South China Sea even though it expects more Chinese vessels to be sent to the area.