Answer : 4. "Japan"
Explanation :

The Philippines and Japan signed a reciprocal access agreement (RAA) to enhance defense ties, focusing on regional stability amid tensions with China. The pact, easing equipment and troop entry for training and disaster response, is Japan’s first in Asia. Philippine and Japanese defense ministers highlighted the importance of cooperation against China’s assertive actions in the South China Sea. This agreement strengthens the defense relationship between two key U.S. allies in Asia.