United States President Barack Obama is now talking tough with Iran, insisting that he is prepared, if necessary, to use military force to stop the country’s atomic ambitions. But if history is any guide, he is more likely to acquiescence to a nuclear-armed Iran.

Indeed, the rhetoric issuing from Washington nowadays is nearly a verbatim copy of the words Obama’s predecessors directed at North Korea. And we all know how well that turned out. (See related story, Tokyo Toughens Stance on Iran)

Consider, for example, the Clinton administration’s declarations on Pyongyang’s proliferation. In late 1993, President Clinton signaled US willingness to thwart North Korea’s nuclear activities by means of war, stating that it “cannot be allowed to develop a nuclear bomb.” His defense secretary shortly thereafter termed the president’s statement an “ultimatum,” adding “we will not let the North Koreans become a nuclear power….nuclear weapons in the hands of North Korea is not acceptable.”

George W. Bush, who framed the invasion of Iraq as an act of counter-proliferation, took a similar hard line toward Pyongyang. He declared categorically in May 2003 that “we will not tolerate nuclear weapons in North Korea.”

Like today, loose talk of military strikes filled the air but the lack of viable options ultimately stayed his hand. When Pyongyang finally did explode a nuclear device in the fall of 2006, he could only repeat that the existence of its arsenal was “unacceptable.”

As the depressing track record with North Korea demonstrates, it is exceedingly difficult to stop a rogue regime determined to develop nuclear capabilities, especially if it located in a strategic part of the world, has powerful patrons, and is able to inflict retribution on important U.S. interests in the region.

Still, this has not kept Obama from borrowing freely from the vocabulary used by Clinton and Bush. In his first press conference as president-elect, he declared that “Iran’s development of a nuclear weapon, I believe, is unacceptable.” In his State of the Union address two months ago, he vowed that “America is determined to prevent Iran from getting a nuclear weapon, and I will take no options off the table to achieve that goal.”

In a media interview the other week, he underscored that he is not bluffing when it comes to the possible use of military force and that “when the United States says it is unacceptable for Iran to have a nuclear weapon, we mean what we say.” And he punctuated this point in a forceful address to the American Israel Political Action Committee, an influential lobbying group in Washington, stressing that “when it comes to preventing Iran from obtaining a nuclear weapon, I will take no options off the table, and I mean what I say.”v Yet the Obama administration’s threat to pick up the cudgel of military action has always an air of unreality. After all, a president determined to wind down George Bush’s wars in the Greater Middle East is quite unlikely to initiate a third one. Ditto for the politician seeking re-election who justifies large-scale troop withdrawals from Afghanistan by declaring that “it’s time to focus on nation-building here at home.” And not to mention the commander-in-chief who unveils the Pentagon’s new strategic guidance by announcing that “the tide of war is receding.”

Nor has it escaped notice in Tehran and elsewhere that for all of the tough-minded rhetoric, Mr. Obama was most reluctant to impose painful economic sanctions on Iran in the first place.

Noteworthy, too, is how the Pentagon leadership is pouring cold water on the military option. Before his retirement last year, Defense Secretary Robert Gates acknowledged that the U.S. armed forces are “exhausted” and pointedly cautioned against launching any new conflicts in the Middle East.

Gates’ successor, Leon Panetta, has warned that a military strike would have “unintended consequences,” touching off global economic instability and broader military hostilities. And the new chairman of the U.S. Joint Chiefs of Staff cautions against attacking Tehran and argues that the Iranian regime is a “rational actor,” suggesting that a nuclear-armed Tehran could be deterred from engaging in provocative actions.

Critics charge that Obama’s recent pronouncements are merely election-year palaver. But it is also important to recognize that he is following a rhetorical playbook laid out by his predecessors. Chances are, he will be no more successful in dealing with a Tehran determined to possess nuclear weapons than they were with Pyongyang.

(David J. Karl is president of the Asia Strategy Initiative, an analysis and advisory firm in Los Angeles.)