(CNN) -- Presumptive Republican presidential nominee Mitt Romney clarified his March remark that Russia is the nation's top foe, saying in an interview which aired Monday on CNN's "The Situation Room with Wolf Blitzer" that Iran potentially poses the greatest national security threat to the U.S.
"The number one national security threat, of course, to our nation is a nuclear Iran," he told CNN's Wolf Blitzer, speaking in Jerusalem about the nearby nation.
Asked about Israel's borders, the broader Israeli-Palestinian conflict, withdrawal of U.S. troops from Afghanistan, the London Olympics, and campaign finance, Romney offered little new policy or criticism of President Barack Obama.
"I'm on foreign soil, and because it's long been a policy of both political parties to leave politics at the water's edge, I'm not going to go through specific foreign policy prescription," he said in response to one question, echoing a similar caveat he affixed to other answers.
But Romney did clarify his comment last spring that Russia "is without question our number one geopolitical foe."
"I'm talking about most of the United Nations and actions of a geopolitical nature, Russia is the number one adversary in that regard," he said. "That doesn't make them an enemy. It doesn't make them a combatant. They don't represent the number one national security threat."
The candidate specifically cited Russia's role in Syria and in international sanctions, saying it "has been slow to move to the kinds of sanctions that have been called for in Iran.
"Russia is a geopolitical adversary but is not an enemy with a -- you know, with... missiles being fired at one another and things of that nature," he said.
The GOP candidate stood by his position that the U.S. should "keep a military option available" to handle Iran, should diplomatic efforts and sanctions not "dissuade them from becoming a nuclear capability nation."
"I certainly hope that our military, under the direction of the president, has, in fact, prepared a whole series of contingency plans, not only to previous Iran from becoming nuclear but to respond were Iran to become more belligerent in its -- in its efforts," Romney said.
The sanctions currently in place "could be, I'm sure, even more punitive."
Obama pointed to those efforts - including new sanctions aimed at the nation's banking and financial systems imposed this year - in a speech last week at the Veterans of Foreign Wars convention.
"We're leading the fight against nuclear dangers," Obama said. "We've applied the strongest sanctions ever on Iran and North Korea -- nations that cannot be allowed to threaten the world with nuclear weapons."
The Obama administration has also stated that all options remain on the table when dealing with a potentially nuclear Iran.
Also in his interview, Romney said the capital of Israel is Jerusalem -- a city at the center of the dispute between the Israelis and Palestinians.
Romney declined to answer questions about what position he holds regarding borders in the search for peace between the Israelis and the Palestinians. Asked if he saw the starting point as the borders which existed prior to the 1967 Six Day War, Romney demurred.
"I'm not being that specific. I'm saying that there will be borders that have to be negotiated and what the starting point is something which will be decided by the parties involved," he said. "What the ending point is will be decided by the parties involved."
The issue of Israeli settlements - which the U.S. has criticized - "is something that should be discussed in private by the American president and our allies," Romney said.
"When we show a diplomatic distance between ourselves and our ally, I think we encourage people who oppose that relationship to seek other means to achieve their ends," he added.
Romney and Blitzer sat for the interview at the historic King David Hotel in Jerusalem on Sunday while the candidate was in the country on his foreign tour. He landed on Monday in Poland and was in London last week.