WASHINGTON (AP) — President Barack Obama snapped back at Sarah Palin and her criticisms about his nuclear defense policy, calling the former Alaska governor “not much of an expert on nuclear issues.”

Obama’s comments came when asked for a response about a Palin critique that he was like a kid poised for a playground fight who said ‘Go ahead, punch me in the face and I’m not going to retaliate. Go ahead and do what you want to with me.”

“I really have no response,” Obama told ABC News. “Because last I checked, Sarah Palin’s not much of an expert on nuclear issues.”

The interview occurred Thursday in Prague, where Obama signed a treaty with Russian President Dmitry Medvedev that orders both nations to shrink their nuclear arsenals. That deal that must still be ratified by the Russian parliament and the U.S. Senate.

Palin was referring to another development on the nuclear front this week, a rewriting of American nuclear strategy.

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Among many other elements of that new plan, the U.S. makes plain that if a non-nuclear nation is in compliance with an international nonproliferation treaty, the United States will not threaten or use nuclear weapons against it.

If such a state were to use chemical or biological weapons against the U.S. or its allies, it would face a potentially devastating conventional military strike by the U.S., but not a nuclear one.

“It’s unbelievable. Unbelievable,” Palin told Fox News on Wednesday. “No administration in America’s history would, I think, ever have considered such a step that we just found out President Obama is supporting today.”

Asked about that criticism from Palin and other Republicans, Obama said: “If the secretary of defense and the chairman of the Joint Chiefs of Staff are comfortable with it, I’m probably going to take my advice from them and not from Sarah Palin.”

Obama departed Prague on Friday and was due back at the White House by the afternoon in Washington.

Meanwhile, Palin, the 2008 Republican vice presidential nominee and a potential presidential candidate in 2012, was set on Friday to rev up Republican activists in a speech at the Southern Republican Leadership Conference in New Orleans.

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