Over the next 48 hours, President Obama will tell Americans—again and again—that Syria is not Iraq. Fair enough. But there are lessons nonetheless. One of them is this: be careful who you go to war with.

Randolph Bourne made the point almost a century ago after his former colleagues at The New Republic insisted that by entering World War I, America could promote democracy at home and abroad. “In every community it was the least liberal and least democratic elements among whom the preparedness and later the war sentiment was found,” Bourne retorted. “Only in a world where irony was dead could an intellectual class enter war at the head of such illiberal cohorts in the avowed cause of world-liberalism and world-democracy.”

I first read those words during the latter stages of Iraq. The New Republic—which I then edited—had justified the invasion in the name of human rights, even though in so doing we had allied ourselves with Dick Cheney. We had insisted that to succeed, the invasion would require a major commitment to postwar nation building, even though we were relying for that effort on Donald Rumsfeld. Needless to say, Bourne’s words stung.

They should sting the supporters of military action in Syria now. I believe President Obama when he says he’s afraid that allowing Bashar al-Assad to use chemical weapons with impunity will shatter a long-standing international norm. But if Congress gives Obama the authority to strike (in violation of the international norm that only the United Nations Security Council can authorize an attack on a foreign country), defending international norms won’t have much to do with it. In lobbying Congress to authorize a strike, Obama has only two arguments with political juice. First (to Democrats): don’t cripple my presidency. Second (to everyone except the most left-wing Democrats): don’t cripple my capacity to threaten military action against Iran. It’s in service of that latter argument that the White House reportedly implored the American Israel Public Affairs Committee (AIPAC)—which one administration official called “the 800-pound gorilla in the room”—to begin lobbying on Capitol Hill for a Syria strike.

That’s where Bourne comes in. Obama may genuinely consider Syria a limited operation aimed solely at deterring Assad, and other creeps, from gassing people in war. But he’s promoting it in partnership with an organization, AIPAC, that is supporting the Syria strike only in order to maximize the threat of a strike against Iran—a strike that could provoke exactly the kind of lengthy, open-ended Middle Eastern war Obama pledges to avoid.

By allying himself with Iran hawks, Obama is getting the Iran-Syria dynamic exactly wrong. What Syria desperately needs is a negotiated peace that ends Assad’s reign of terror and produces a political arrangement that keeps its various communities safe. Iran stands in the way of that because its leaders—who face hostile Sunni Arab neighbors and a hostile United States—don’t want to lose their strongest regional ally. The more menacing the United States and its allies appear, therefore, the tighter Iran will cling to Assad. If there’s any chance of persuading Iran to cut Assad loose, it will happen only when the clerics in Tehran decide they can do so without endangering their own survival. And that’s more likely if America threatens Iran less, not more.

Since Syria is caught in the middle of an American-Iranian (and to a lesser degree, American-Russian) cold war, it’s worth remembering what ended the last Cold War. In the 1980s, Mikhail Gorbachev decided that the Soviet Union could no longer afford to prop up unpopular regimes in Eastern Europe. But to cut Eastern Europe free, Gorbachev had to answer hard-liners who had long argued that the USSR needed a ring of clients to protect it against another attack from the West. That’s why Ronald Reagan’s willingness to embrace Gorbachev and negotiate far-reaching arms-control deals—despite bitter criticism from conservative politicians and pundits—proved so important. As Reagan himself argued, “I might have helped him see that the Soviet Union had less to fear from the West than he thought, and that the Soviet empire in Eastern Europe wasn’t needed for the security of the Soviet Union.” By helping show Gorbachev that he could safely release Eastern Europe, Reagan helped end the Cold War. And when the Cold war ended, so did civil wars across the globe because the U.S. and USSR no longer felt that their own security required arming one side.

Today, President Obama’s real strategic and moral imperative is not killing a few Syrian grunts to punish Assad for using chemical weapons. It is ending the Middle Eastern cold war that fuels Syria’s savage civil war, just as the global Cold war once fueled savage civil wars in Angola, El Salvador, and Vietnam. It’s possible that strengthening Syria’s rebels and sanctioning Iran could further that goal, just as Reagan’s military buildup showed Moscow the cost of its Cold War with the United States, but only if such efforts are coupled with a diplomatic push that offers Iran’s leaders a completely different relationship with the United States, one that offers them security and status absent a nuclear weapon and no longer requires them to cling to Bashar Assad. By striking Syria, Barack Obama is making that harder. By doing so in alliance with groups that oppose any thawing of the U.S.-Iranian cold war absent total Iranian capitulation, he’s making it hard er still.

If the president wants to convince Americans that Syria is not a prelude to a bigger war, he needs to explain his strategy for avoiding one with Iran. His problem is that his key allies in supporting a Syria strike don’t want to avoid war with Iran—at least not if doing so requires real concessions from the United States. In 1917, Randolph Bourne pointed out how hard it is for America to fight limited wars for liberal aims. Almost 100 years later, I fear, events are again proving him right.