The new U.S.-Russian agreement on Syria’s chemical weapons has placed the campaign to launch strikes against Syria on hold. Proponents of war are not happy about that development, and they both hope and expect that the agreement will ultimately unravel. Senators John McCain and Lindsey Graham immediately denounced the agreement, arguing that a failure to attack Syria will convey a message of U.S. weakness to Iran.

It is the latest indication that for many proponents of assaulting Bashar al-Assad’s forces, Syria is not the primary target of U.S. wrath. It is merely the prelude to the main event: confronting and undermining Iran. “If we don’t get Syria right,” Senator Graham charged, “Iran is surely going to take the signals that we don’t care about their nuclear program.” Weekly Standard editor William Kristol is only a little more flagrant than his ideological colleagues in expressing the view that Iran is the real target. A “yes” vote to authorize force against Syria, he stated, “can be explained as a vote to stop the Iranian nuclear program. Syria is an Iranian proxy for Iran’s ability to move ahead unimpeded in its acquisition of nuclear weapons. To bring this point home, soon after voting to authorize the use of force against the Assad regime, Republicans might consider moving an authorization for the use of force against the Iranian nuclear weapons program.”

But even Obama administration officials who may not be seeking war with Iran insist that attacking Syria would “send a message” to Tehran that Washington is deadly serious about preventing that country from acquiring nuclear weapons. Conversely, they argue, a failure to act against Assad would encourage the Iranian mullahs to believe that the United States is a paper tiger. On several weekend television news programs just before Moscow disrupted matters by offering its chemical weapons proposal, White House Chief of Staff Denis McDonough made such arguments.

Anyone watching those interviews might have experienced a sense of déjà vu. The notion that Iran would be intimidated or somehow transformed if the U.S. attacked another Middle East country is not a new idea; it was a staple of hawkish arguments during the prelude to the Iraq War from late 2001 to early 2003. Richard Perle insisted that having already destroyed the Taliban in Afghanistan, moving against Saddam’s regime would send the message to Iran (and other supporters of terrorism such as Syria and Libya) that “‘You’re next.’ Two words. Very efficient diplomacy.”

Washington Post columnist Charles Krauthammer contended that the United States could best accelerate an anti-clerical revolution in Iran by conducting successful military campaigns in nearby states, especially Iraq. “Overthrowing neighboring radical regimes shows the fragility of dictatorship, challenges the mullahs’ mandate from heaven and thus encourages disaffected Iranians to rise,” Krauthammer argued. “First, Afghanistan to the east. Next, Iraq to the west.” The ubiquitous Bill Kristol insisted that the potential “political, strategic and moral rewards” of invading Iraq would be great. Among other benefits, a “friendly, free, and oil-producing Iraq would leave Iran isolated.” American Enterprise Institute writers Gary Schmitt and Tom Donnelly predicted: “Defeating the Saddam/Bin Laden axis will send a broader message as well. It will deter Iran, Syria, and the other part-time members of the anti-American coalition in the Middle East.”

Clearly, defeating Saddam Hussein did not cow the Iranian government—much less inspire a popular revolution to oust the mullahs. Indeed, it seemed to have the opposite effect. Tehran doggedly continued to pursue its nuclear program, and with the election of Mahmoud Ahmadinejad as president, the Iranian government became even more recalcitrant and hostile toward the United States. One would think that given that track record, pundits and foreign-policy activists might be a bit cautious about advancing the thesis that taking a hard line with Syria would have a beneficial impact on Iran’s behavior.

To be fair, the current “intimidation” thesis is a shade more logical than the earlier version regarding Iraq. Syria is at least an Iranian ally. Saddam’s Iraq was Iran’s mortal adversary. Eliminating Saddam’s regime did not intimidate Tehran, it removed the principal strategic counterweight to Iranian power in the region. In other words, the United States did the clerical regime a big favor.

It is a good sign that the notion of attacking Syria to thwart Iran is encountering vocal resistance from journalists and policy experts. CNN’s Candy Crowley openly challenged McDonough on his argument. “I’m confused by this idea that somehow the U.S. backing up words with a missile strike into Syria sends a message to Iran,” Crowley pressed. “We went to Iraq with more than 100,000 troops. We took out a leader. It didn’t affect their behavior at all. Why would a missile strike in Syria do so?”

That kind of healthy skepticism was far too rare in the prelude to the Iraq War. Such challenging questions might help spare the United States another unnecessary, counterproductive military crusade in the event that the Russian diplomatic initiative ultimately fails. The arguments for attacking Syria are extremely weak, and the notion of doing so to intimidate Iran is an especially poor, recycled justification. We should treat it with the scorn it deserves.

Ted Galen Carpenter, a senior fellow at the Cato Institute and a contributing editor to The National Interest, is the author of nine books and more than 500 articles and policy studies on international issues.