2:58 pm ET
By Mark Landler


President Obama with President Park Geun-hye of South Korea at the Nuclear Security Summit in Washington on Thursday. Credit Doug Mills/The New York Times

WASHINGTON — A White House official said on Thursday that it would be “catastrophic” to adopt a proposal by Donald J. Trump, the Republican front-runner, that Japan and South Korea manufacture their own nuclear bombs to deter North Korea.

Benjamin J. Rhodes, the deputy national security adviser and one of President Obama’s closest aides, said, “Frankly, it would be catastrophic were the United States to shift its position and indicate that we somehow support the proliferation of nuclear weapon to additional countries.”

Mr. Rhodes, speaking at the Nuclear Security Summit here convened by Mr. Obama, said Mr. Trump’s proposal was “not particularly relevant to the very serious discussions we’re having here.” But he was withering in his response to the idea, which he said would undercut decades of nonproliferation policy.

“The entire premise of American foreign policy as it relates to nuclear weapons for the last 70 years has been focused on preventing the proliferation of nuclear weapons,” Mr. Rhodes said. “That has been the position of bipartisan administrations, of everybody who has occupied the Oval Office.”

Mr. Trump first broached the issue of a nuclear-armed Japan and South Korea in an interview with The New York Times last week, putting it in the context of his argument that the United States should no longer bear the full burden of defending its East Asian allies. He defended his comments in a town-hall-style meeting in Milwaukee on Tuesday that was televised by CNN.

“You have so many countries already — China, Pakistan, you have so many countries, Russia — you have so many countries right now that have them,” Mr. Trump told the host, Anderson Cooper. “Now, wouldn’t you rather, in a certain sense, have Japan have nuclear weapons when North Korea has nuclear weapons?”

Earlier this week, a top Japanese government official reiterated Japan’s policy that it would not possess nuclear weapons.

Find out what you need to know about the 2016 presidential race today, and get politics news updates via Facebook, Twitter and the First Draft newsletter.