Trump considering withdrawal from 68-year-old treaty with Japan: report
Japan's Prime Minister Shinzo Abe meets with U.S. President-elect Donald Trump (R) at Trump Tower in Manhattan, New York, U.S., November 17, 2016. (Cabinet Public Relations Office)

President Donald Trump has been privately talking about withdrawing from the postwar defense treaty with Japan, according to three sources familiar with the matter.

Trump is telling confidants the treaty is unfair to the U.S. because it promises to help if Japan was ever attacked, but doesn't require Japan to come to America's defense, the sources told Bloomberg.

So far, the president hasn't taken any step toward pulling out of the treaty, which was signed in 1951, and administration officials insist that move would be highly unlikely.

Trump's criticism of U.S. security pacts has alarmed allies around the world, but so far he hasn't tried to back out of those agreements like he has with trade pacts.

Japanese Chief Cabinet Secretary Yoshihide Suga told Bloomberg that the security framework was at the core of the country’s alliance with the U.S.

“There is no talk at all of a review of the Japan-U.S. security alliance as has been reported in the media,” Suga said.

Ending that treaty would risk handing over security in the Western Pacific to China and potentially risk a new nuclear arms race if Japan decided it needed to protect itself from nuclear-armed neighbors.

Trump will travel to Japan on Wednesday for the G-20 summit in Osaka