MEDFORD, Mass. — THE use of nerve gas in Syria is abhorrent, and those within the Syrian military command who ordered it are war criminals. But it is folly to think that airstrikes can be limited: they are ill-conceived as punishment, fail to protect civilians and, most important, hinder peacemaking.

The use of chemical weapons should be punished. No country should remain neutral when human beings are gassed. This is one thing on which the United States, Russia and Iran can agree. But the most convincing punishment would come through an international war crimes tribunal outside Syria.

Syrian civilians deserve protection from murder, but bombing won’t deliver it. Efforts to protect civilians through military action have a checkered history that reveals a fundamental truth: their success depends on whether they reinforce a political plan. From the creation of safe havens for Kurds in northern Iraq in 1991 to the campaign that ousted Muammar el-Qaddafi in Libya in 2011, effective interventions support diplomacy; they don’t replace it.

The United States government dispatched nearly 30,000 troops to Somalia in 1992 and 1993 for humanitarian purposes, but the operation came to grief when the Americans stumbled into a partisan conflict, caused the deaths of hundreds of Somalis and lost 42 service members, including 18 killed in one culminating battle. The NATO bombing of Belgrade in 1999 forced the Serbs to withdraw from Kosovo, but only after the campaign was expanded and the United Nations took responsibility for administering the area. In Afghanistan and Iraq, the United States and its allies got dragged into long and difficult wars. The consequences of NATO action in Libya are still uncertain.