WASHINGTON -- President Trump's decision last year to launch 59 Tomahawk cruise missiles at a Syrian air base was intended to send the Assad regime a message that its use of chemical weapons would no longer be tolerated. But the strikes also had a broader purpose: showing other regimes that the Obama era of U.S. weakness was over, and that America's adversaries would have to adjust their calculations about our willingness to act in response to their provocations.

Now, a year later, the Assad regime has reportedly defied Trump by its apparent launch of another chemical weapons attack. Once again, how Trump responds will have consequences far beyond Syria.

With a high-stakes summit with North Korean dictator Kim Jong Un coming up, Trump needs to keep in mind how his next move in Syria will be seen not just in Damascus, Tehran and Moscow but also in Pyongyang. He should use his next strikes on Syria both to punish dictator Bashar Assad and to demonstrate to Kim what might happen to North Korea if it continues to pursue nuclear intercontinental ballistic missiles (ICBMs) that could destroy American cities.

Last year, Trump delivered a measured, proportionate response to Assad's chemical attack, hoping this would deter the Syrian dictator. According to retired Gen. Jack Keane, former vice chief of staff of the U.S. Army, "What we shouldn't do is another measured, proportionate response yet larger. That won't deter him." Instead, Keane says, "What we have to do is destroy all his capabilities that deliver those weapons."

The United States should take out all of Assad's rotary and fixed-wing aircraft, Keane says, and destroy all of his airfields, aviation fuel at those airfields, aviation maintenance equipment and aviation munitions. "If he still has artillery-delivered chemical weapons," Keane says, "then we should take down his artillery as well."

In other words, another "bloody nose" strike -- even a bigger one -- is not enough. We need to conduct large-scale operations that will destroy Assad's weapons-of-mass-destruction capability. Such an attack would eliminate Assad's ability to commit chemical weapons atrocities.

Just as importantly, it would also provide an unspoken preview for Kim of what could happen to his nuclear and missile programs if he persists in developing and testing the capability to threaten the United States with nuclear destruction.

Sen. Lindsey O. Graham, R-S.C., has suggested that Trump should also consider taking out Assad with a "decapitation" strike. "Assad and his inner circle should be considered war criminals, legitimate military targets," Graham said this week. "If you have the opportunity to take him out, you should."

Graham is absolutely right that Assad and his cronies are legitimate military targets, but Trump should hold off on such a strike -- at least initially -- and instead warn Assad that he reserves the right to hit leadership targets directly if he retaliates.

Why? Because Trump wants Kim to see that a similar military operation against North Korea's weapons of mass destruction would not necessarily result in regime destruction -- as long as Kim does not retaliate.

By acting decisively in Syria, Trump also has an opportunity to send a message not just to North Korea but also to China that he is not bluffing when he threatens to act against Kim's regime. Chinese President Xi Jinping was with Trump at Mar-a-Lago when he launched last year's strikes against Assad, and the Chinese leader responded by stepping up economic pressure on Pyongyang.

A large-scale operation to eliminate Assad's capability to produce weapons of mass destruction would be a wake-up call to China that Trump is willing to take similar action against North Korea; it would also create an incentive for Xi to step up the pressure for denuclearization.

Trump also needs to stop talking about withdrawing U.S. forces from Syria. An American withdrawal would not only allow Assad to escalate his brutal campaign of atrocities in Syria, but also it would tell Pyongyang that Washington does not have the stomach to see its military campaigns through.

If Trump can't keep 2,000 U.S. troops in Syria, Kim would calculate, he would hardly have the fortitude to see through a much more difficult military intervention against North Korea.

Trump has an opportunity to end Syria's ability to massacre innocent men, women and children with weapons of mass destruction. But he also has a chance to show Pyongyang before the summit meeting that his threats of military action are more than bluster.

The success or failure of that meeting depends on whether Kim believes Trump is serious about taking military action -- which is why Kim will be carefully watching what Trump does next in Syria.