(CNN) - Former Secretary of Defense Robert Gates on Thursday cautioned against some of the foreign policy rhetoric on the campaign trail, particularly words used by the top two Republican presidential frontrunners.
Asked about Newt Gingrich, who calls for a regime change in Iran to prevent the development of a nuclear weapons program, Gates stressed the complexity of the situation in an interview with CNN's "John King, USA."
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"This is one of the toughest foreign policy problems I have ever seen since entering the government 45 years ago, and I think to talk about it loosely or as though these are easy choices in some way, or sort of self-proclaim obvious alternatives, I just think is irresponsible," Gates said.
His comments came the same day the current Defense Secretary, Leon Panetta, said there is a growing likelihood Israel could attack Iran sometime this spring in an effort to destroy its suspected nuclear weapons program, according to a senior administration official.
While Gingrich has said the United States should only take military action against Iran as a last recourse, the former House speaker has strongly suggested that steps must be taken to prevent the country from developing a nuclear weapon.
"Iran is not going to get a nuclear weapon. All the world can decide is whether they help us peacefully stop it or they force us to use violence," Gingrich said on CNN in December. "But Iran is not going to get a nuclear weapon."
Gates, who retired from his longtime civil service career in June, said Thursday the situation with Iran is laden with a "very difficult and dangerous set of choices."
"Those who say we shouldn't attack, I think, underestimate the consequences of Iran having a nuclear weapon," he said. "And those how say we should, underestimate the consequences of going to war."
Gates also argued against a line used by Mitt Romney, who has criticized President Barack Obama for being too soft and uses "pretty please" foreign policy.
But Gates, who also served as Defense Secretary under President George W. Bush, was quick to point out that Obama issued the deployment of 60,000 additional troops to Afghanistan and ordered the killing of Osama bin Laden, as well as a number of other al Qaeda operatives.
"You know sometimes things get pretty heated in campaigns, but I think the reality is there is an acknowledgment on people's part around the world that this president is willing to use military force when our needs require it," he said.
– CNN's Ashley Killough contributed to this report.