On April 8, after learning of the alleged Syrian regime's use of chemical weapons against a civilian neighborhood, President Trump tweeted that Syrian President Bashar Assad would pay a “big price.” The last time the Syrian government so blatantly used chemical weapons, Trump ordered a barrage of Tomahawk cruise missiles to strike at the base responsible for the chemical weapons attack. In the wake of the latest incident, however, many analysts have pointed out that last year’s response neither deterred Assad nor undercut his momentum against the Syrian opposition and questioned whether a new missile barrage would be any different.

Nor can Assad expect any serious repercussions at the United Nations given Russia’s willingness to protect him at all costs. “What’s the point of trying to shame such people?” U.S. Ambassador to the U.N. Nikki Haley said , “Pictures of dead children mean little to governments like Russia.”

What can Trump do? Former President Barack Obama’s unwillingness to enforce a red line on chemical weapons use hemorrhaged his credibility and convinced Assad and his Russian patrons that they could, quite literally, get away with murder. But if he is serious about restoring a deterrent to the use of chemical weapons, then he should not rely on some symbolic cruise missile response. That was his tactic last year, but its lasting impact was negligible. For that matter, that was Bill Clinton’s tactic of choice in 1998 after al Qaeda attacked U.S. embassies in Kenya and Tanzania, and a middle-of-the-night cruise missile strike into Afghanistan did nothing to convince al Qaeda and their Taliban protectors to cease their terrorist activities ahead of the Sept. 11 attacks.

Targeting Assad, however, would be the ultimate deterrent to dictators who might want to go down the same path. There is nothing absolute about the prohibition on targeting world leaders. President Gerald Ford issued Executive Order 11905, which declared that “no employee of the United States Government shall engage in, or conspire to engage in, political assassination,” but that is of only questionable application to targeting a commander in chief militarily. While President Abraham Lincoln administration had in 1863 instructed Union forces not to engage in assassination, the subsequent international agreements joined by the U.S. (the 1907 Hague Convention and the 1949 Geneva Conventions) were vague on the question of assassination.

Regardless, there is ample precedent which suggests that Assad could be a target. In 2010, the Iraqi government executed Ali Hassan Abd al-Majid al-Tikriti, better known as “Chemical Ali,” for his complicity in the use of chemical weapons against the Kurds and, of course, the United States supported the trial of Iraqi dictator Saddam Hussein for a series of outrages against civilian populations.

Want to use cruise missiles? As Assad leads Syria to ruin, there is no reason why his shiny and ostentatious palace should remain standing on a mountaintop above Damascus. And while Russia warns the United States not to retaliate in Syria, permanently removing Assad from the battle field would leave Moscow no choice but to begin serious negotiations on who comes next. Simultaneously, the Kremlin would think twice about allowing its other clients in the future to stray so far from the rules of war.

Certainly, a decision to target a foreign leader should not be taken lightly. Some critics will question whether such targeting would open enemies to try to assassinate U.S. leaders. Let’s put aside moral equivalence — the United States is not Syria.

Rather, enemies already do try to target the U.S. leadership and other world leaders. During the Cold War, the Soviets were complicit in an assassination attempt on Pope John Paul II. And President Bill Clinton ordered the bombing of Iraq after evidence emerged that Hussein had sought to assassinate President George H.W. Bush. The Islamic Republic of Iran sought in 2010 to kill the Saudi ambassador to the United States by using a car bomb at a popular Capitol Hill eatery frequented by U.S. senators.

Then there is a question about whether Assad, the devil we know, is better than the devil we don’t. Let’s put aside the fact that such a calculation largely went out the window once the devil began using sarin gas on women and children. It is true that the Syrian opposition, with the exception of the Syrian Kurds, has largely radicalized well beyond any definition of moderation. Their inability to work together makes it unlikely that they will be able to seize full control over Syria. More likely, a member of Assad’s inner circle will step in and take the reins and make it possible for all sides to save face and begin discussing a provisional government.

A cruise missile strike that kills Assad will not alone bring peace. But it will enable Syrians to begin a new discussion while simultaneously signaling other world leaders that they do not have immunity should they use weapons of mass destruction.

Michael Rubin (@Mrubin1971) is a contributor to the Washington Examiner's Beltway Confidential blog. He is a resident scholar at the American Enterprise Institute and a former Pentagon official.