The term "red line" has been tossed around so much that its meaning is often lost. But there are certain international norms that must not be crossed or, if they are, must result in swift and terrible punishment for the offending country. Such is the case with the use of chemical weapons, which have long been banned by civilized nations. It's not just that they are brutal, which, of course, they are, but because they are a blunt instrument that targets civilians and, if tolerated in one part of the world, could spread across the globe as a kind of low-cost, low-tech nuclear option — an affordable tool of terror.
To his credit, President Donald Trump tweeted an appropriate level of outrage at Syrian President Bashar Assad, whom he called an "animal," and warned Iranian officials and Russian President Vladimir Putin that they would have a "big price to pay" for backing him after the chemical attacks near Damascus on Saturday that took the lives of dozens. But how big a price — or perhaps how long-term a price — they'll pay is unclear. President Assad may well have been emboldened into action, at least in part, because President Trump has spoken so forcefully about withdrawing thousands of U.S. troops form eastern Syria where they have been fighting the Islamic State.
It appears Israel has already taken the lead in responding to Mr. Assad's actions against his own people by launching an airstrike against a Syrian military base early Monday. Surely, it would come as no surprise if President Trump authorized a similar level of military action in the coming days. One year ago, he dispatched 59 Tomahawk cruise missiles at Syrian targets following that country's use of chemical weapons that killed more than 100 people. Whether that action altered the Syrian government's behavior may be debatable, but it was the appropriate, properly calibrated response.
Yet if President Trump takes similar action and nothing more, then continues his push to reduce U.S. military presence in that country's civil war, he might as well do nothing at all. Mr. Trump is essentially in the same trap that ensnared Barack Obama during his two terms in the Oval Office. Mr. Obama used the actual words "red line" to warn President Assad about the use of chemical weapons. Ultimately, President Obama tried to navigate a middle path of pushing Russia and Syria into voluntarily reducing the country's chemical weapons arsenal (an accomplishment at the time but not a lasting one), but he offered no real remedy for the Syrian humanitarian crisis. He rightly opposed Mr. Assad's continuing as Syria's leader but was justifiably suspicious of the strength and unity of rebel forces as well.
The irony, of course, is that Mr. Trump has been critical of Mr. Obama for not intervening more forcefully in the Syrian civil war, but he has also been critical of prolonging U.S. involvement in the conflict. So which is it this time? Is Mr. Trump just going to get by with some tough talk — notable as the president's first-ever tweet critical of Mr. Putin might have been — and then go back to de-escalation? Or will the president, perhaps encouraged by a more hawkish foreign policy team, reverse course and deepen U.S. military involvement in the region? He would seem to be at a crossroads with only unattractive choices.
As painful as it may be — and as distant from Mr. Trump's noninterventionist "America First" foreign policy script — the U.S. can't reward Mr. Assad by withdrawing troops and potentially giving Russia even more room to impose its will on the region. If this sounds like a Cold War script, then perhaps that's because it is. It's hard to determine exactly who are the U.S. allies in Syria, it's pretty clear that Mr. Assad isn't one of them. There's no question that after seven years of conflict, Syria is broken. Removing U.S. forces at this time won't help fix that. No matter what kind of missile launch or other one-time military attack Mr. Trump unleashes on the Assad regime, the president must also make clear that the U.S. is staying put until the country is in more rational hands and that those hands do not belong to Mr. Assad.