A second group of about 200 U.S. Marines and sailors to spend six months in Australia will be leaving Hawaii this weekend, the Marine Corps said Friday.

They are going as part of a policy President Barack Obama announced in 2011 to rotate up to 2,500 Marines through an Australian training hub to help allies and protect American interests across Asia.

The Marines and sailors are from Lima Company, 3rd Battalion, 3rd Marine Regiment, based in Kaneohe Bay. They’re scheduled to leave this morning for Darwin in northern Australia, where they will train and participate in exercises with Australia and New Zealand, Marine Corps Forces Pacific said in a news release.

The first group of about 200 Marines went last year.

The rotation plan allows the United States to keep a sustained force on Australian bases and position equipment and supplies there. That gives the U.S. the ability to train with allies in the region and respond more quickly to humanitarian or other crises.

U.S. officials have said they don’t plan to create a permanent American military presence in Australia.

The U.S. Air Force also has been sending forces to Australia. Last year it sent a B-52 bomber and KC-135 refueling tanker from Guam to Darwin to train with Australia’s air force.

China, which is Australia’s most important trade partner, has criticized deepening U.S.-Australian military ties as a return to Cold War divisions that risk the region’s peace and security.

The Australian government says the U.S. military presence isn’t aimed at containing China. It has said it’s open to China participating in joint exercises in Darwin in the future.

U.S. commanders have stressed they aim to have a cooperative relationship with China and are not trying to contain the Asian nation as it emerges as a global power.