Fox News’ Tucker Carlson, after a friendly interview Tuesday with anti-war leftist Glenn Greenwald, challenged anyone supporting American military action in Syria to define what U.S. interests there might be.

The answer is fairly straightforward.

The United States cannot allow Syria to fall into Iranian hands. If it does, Iran will extend its military influence into the Mediterranean, threatening American bases as well as American allies. It will also strengthen its emerging position as a regional power that threatens Israel and the Sunni Arab states.

In addition, the U.S. has a strong interest in punishing the use of chemical weapons. Granted, that is an interest shared by the international community in general, but few nations other than the U.S. are capable of carrying out that punishment. If the U.S. fails to respond to the Syrian regime’s alleged use of chemical weapons, the use of such weapons will become more widespread, including by terrorists.

Finally, the U.S. has an interest in protecting the Kurdish population of the region, which provided the most effective ground forces in fighting the Islamic State (ISIS) in Syria, and which is broadly pro-American. If the U.S. were to abandon the Kurds now, many Kurds would be in danger, and few groups would take risks on America’s behalf in future.

That does not mean the U.S. must send troops to Syria, or that it must topple the Assad regime. These are alternatives that the U.S. might use in pursue of its interest, but there are alternatives — such as, for example, arming the Kurds and perhaps supporting their ambitions for independence.

Those who emphasize these interests are not pushing for war. On the contrary, many advocates of a U.S. role in Syria want to avoid a wider war that might be inevitable if Iran takes effective control of the country and uses its power to threaten its rivals. As Caroline Glick argued recently, the effect of such a war could be devastating to the American economy, whether or not the U.S. is involved.

These answers seem obvious enough that one wonders what Carlson’s motivation is for opposing U.S. involvement in Syria so strenuously.

He famously turned against the Iraq war and vowed never to support U.S. involvement in such a conflict again, so perhaps that is the reason for his current position.

Still, given the lessons of recent experience in Iraq, where a hasty U.S. withdrawal under President Barack Obama led to the rise of ISIS and the expansion of Iranian power, it would seem the onus is actually on Carlson to explain how his position would not risk American national security.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He was named to Forward’s 50 “most influential” Jews in 2017. He is the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.