The U.S. missile attack on a Syrian air base can be read as President Donald Trump sending this message about North Korea: "When I make a threat, I am serious about it."

North Korea, which fired a ballistic missile into the sea one day before Trump's summit meeting with China's President Xi Jinping, was a top agenda for the first meeting between the leaders of the world's two largest economies.

Analysts told CNBC after the attack on Syria that while the latest development replaced North Korea as the immediate security risk, it elevates concerns about the hermit nation.

"I think it actually raises the importance of the North Korea issue. Remember Kim Jung Un recently used a nerve agent to assassinate his half brother, allegedly, in Malaysia, showing the U.S. it is willing to do military action unilaterally. … I think it definitely raises the stakes for China in looking at what the states might do about North Korea," David Dollar, senior fellow at the Brookings Institute, said on CNBC's "Street Signs."

"I don't think it's deliberately aimed at China but obviously the U.S. felt it didn't need to wait until after that summit. They didn't hesitate to do it in the middle of the summit so that's sending a certain kind of message to Xi Jinping," he added.

Reva Goujon, vice president of global analysis at Stratfor, said the Tomahawk missile attack signaled that Trump is "willing to take action" after wide speculation that he is a president who "is all bark and no action."

"This is Trump saying, 'No, I am a man of my words. When I make a threat, I will follow through.' That's certainly something the Chinese and North Koreans will be thinking about," she said on CNBC's "Street Signs."