U.S. Republican presidential candidate Donald Trump on Sunday renewed his calls for allies to pay more for American defense support.

"We protect Japan. We protect Saudi Arabia," Trump said at the annual bikers' rally in Washington, repeating his long-running point that the U.S. has been providing protection for wealthy nations like South Korea and Japan in exchange for little and should end such protection unless those countries agree to pay more.

"It's going to be a whole new ballgame," Trump said. "We send them wheat. They send us cars. I'm not angry at them. I'm angry at our grossly incompetent president who allowed this to happen."

Trump did not mention South Korea, but it is not believed to be any meaningful omission.

Maximizing U.S. interests through negotiation is the No. 1 point in Trump's "America First" foreign policy. Trump and his aides have repeatedly emphasized that the businessman is an excellent negotiator and is ready to use the skill to regain American interests lost under Democrat administrations.

But such a stance has unnerved foreign countries, especially such allies as South Korea and Japan, as Trump has said that the U.S. should be prepared to end its protection of allies unless they pay more. He even suggested allowing South Korea and Japan to develop their own nuclear weapons as a way to reduce U.S. security burdens.

South Korea currently pays about half the costs, about $900 million a year, to help finance the troop presence, and U.S. officials, including new U.S. Forces Korea Commander Vincent Brooks, said it would cost more to keep those troops stationed in the U.S. than it does in Korea.

Trump's top foreign policy adviser, Walid Phares, said in a recent interview with Yonhap News Agency that Trump's remarks made as a candidate should be taken as an expression of principles, rather than policy, meaning that such extreme scenarios as a troop pullout are only for negotiation purposes. (Yonhap)