U.S. President Donald Trump’s stunning order for a missile strike on a Syrian military airfield Friday may change the calculus on how China views his threats of unilateral action against nuclear-armed North Korea, experts say.

The U.S. launched a barrage of 59 cruise missiles against a Syrian military airfield in response to the chemical weapons attack Tuesday by Damascus in Khan Sheikhoun, the Pentagon said.

The strike came amid Trump’s much-anticipated first meeting with Chinese President Xi Jinping at the U.S. leader’s Mar-a-Lago resort in Florida.

North Korea’s improved missile and nuclear weapons programs were expected to top the agenda at the two-day meeting

Prior to the summit, Trump had urged Beijing, the North’s main patron, to help rein in its neighbor, but had also said the U.S. would be willing to go it alone if China proves to be an unwilling partner.

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The chemical attack by the regime of Syrian President Bashar Assad, the latest atrocity in the country’s brutal civil war, reportedly killed and injured hundreds of civilians, including women and children.

Pentagon spokesman Capt. Jeff Davis called the strike “a proportional response to Assad’s heinous act.”

“The strike was intended to deter the regime from using chemical weapons again,” Davis said. “The use of chemical weapons against innocent people will not be tolerated.”

Security experts said the move by Trump shows that the U.S. president appears willing to back up his hard-line rhetoric against U.S. enemies with military action — a shift that could have implications for North Korea and the regime of leader Kim Jong Un.

“China now likely views Trump’s threat to take unilateral action against North Korea as more credible,” said M. Taylor Fravel, an associate professor of political science in the security studies program at the Massachusetts Institute of Technology.

“China may be more willing to take actions, either by itself or with others, to slow the pace or even halt Pyongyang’s nuclear and missile programs,” Fravel added. “But North Korea is a much greater challenge militarily that cannot be solved with symbolic strikes.”

Any military strike on North Korea — especially against its leadership or nuclear sites — would likely be followed by a counterattack on Seoul that would devastate the South Korean capital, something Pyongyang has long threatened to carry out if it comes under attack.

Youngshik Daniel Bong, a research fellow at the Yonsei University Institute for North Korean Studies in South Korea said the strikes have “generated enormous impact.”

“The missile strikes must have been discussed and decided by the Trump administration when it was preparing for the summit meeting with President Xi.”

These discussions, he said, likely “included Secretary of State Tillerson and Secretary of Defense Mattis. That means, it is not just President Trump acting bold. It means there is a very high level of internal unity among top officials of the administration and the president in favor of bold actions that will bring actual results, not the usual resorting to diplomacy and multilateral cooperation.”

The threat of the North’s improving missile program has also stoked concern in Tokyo.

On Wednesday, the North conducted a failed missile test-launch. It was the latest in a spate of tests this year, including the near-simultaneous firing of four ballistic missiles into the Sea of Japan last month — a move the North said was a rehearsal for attacking U.S. bases in Japan.

Those missiles, three of which fell into Japan’s exclusive economic zone, flew about 1,000 km. Prime Minister Shinzo Abe characterized that test as “a new level of threat.”

On Friday, Abe offered support for the U.S. strike. In an apparent reference to North Korea’s efforts to develop nuclear arms, Abe also said Japan “highly appreciates” the Trump administration’s commitment to maintaining global order and working with its allies at a time when “the threat from weapons of mass destruction is also growing more serious in East Asia.”

Bonnie Glaser, an Asia expert at the Center for Strategic and International Studies think tank in Washington, said that while Trump has demonstrated his decisiveness on the use of force, Syria and North Korea represent vastly different scenarios.

“There is no doubt that the Syria strike will influence China’s assessment of Trump,” Glaser said. “But North Korea is very different from Syria. Any strike on North Korea risks an artillery barrage against the South. I don’t think the U.S. has any good military options. But the Chinese can’t rule it out, of course.”

Still, Glaser said she remains skeptical that the strikes will compel China to do something that it wasn’t prepared to do before the strike on Syria.

Nevertheless, the meticulously orchestrated Trump-Xi summit — and any fruitful results — will likely be eclipsed by Syria and the spotlight it casts on Trump.

“Xi will likely be embarrassed by being overshadowed during an important trip that had been carefully planned,” said MIT’s Fravel. “Xi had hoped to demonstrate his own stature as a statesman, meeting with a United States president who had criticized China harshly on the campaign trail.”

Information from Kyodo added