PEARL HARBOR, Hawaii (AP) - Some 25,000 sailors and other military personnel from 22 nations are converging on Hawaii to practice hunting for submarines and catching pirates over the next five weeks in the world's largest naval exercises.

The U.S. Pacific Fleet hosts the Rim of the Pacific exercises every two years. The series of drills started Friday.

Countries from Japan to Tonga and Russia to Chile are sending 42 surface ships, six submarines and 200 aircraft to participate.

Trainees will practice clearing mines, disposing of explosives and aiding civilians during natural disasters, among other exercises.

This year, the Navy will use a cooking oil and algae biofuel blend to power some of the U.S. vessels and aircraft used in the drills.

The exercises come as the U.S. military refocuses attention on the Asia-Pacific region.