U.S. President Donald Trump and his Chinese counterpart finally met Thursday with Trump saying he has "developed a friendship" with Xi Jinping, but undercurrents ran deep at state dinner in Mar-a-Lago as the U.S. military attacked a Syria-government airfield when the meal was underway. The timing was unlikely to be much of a coincidence, analysts told CNBC. "I don't think it was deliberately aimed at China. But obviously, the U.S. felt that it didn't need to wait until after that summit, so they didn't hesitate to do it right in the middle of the summit. That's definitely sending some kind of message to Xi Jinping," said senior fellow at the Brookings Institution, David Dollar. "It definitely raises the stakes for China in looking at what the United States might do about North Korea," he added.

China ally North Korea launched a Scud-ER ballistic missile from the port city of Sinpo on Wednesday in what is seen as an act of defiance before the meeting between the two leaders, and just days after Trump himself told the Financial Times that the U.S. will take unilateral action to end North Korea's nuclear threat unless China raises the pressure on Pyongyang. The attack on Syria was thus a signal to North Korea that "when I make a threat, I'm serious about it," said Francesco Mancini, assistant dean at the Lee Kuan Yew School of Public Policy in Singapore. With talk rife in the Chinese press ahead of Xi's visit that Trump was all talk and no action, Trump can now say: "'No, I am a man of my words, when I make a threat, I will follow through' and this is certainly something the Chinese and the North Koreans will be thinking about," vice president of global analysis at Stratfor, Reva Goujon, told CNBC's "Street Signs".

Meanwhile, the state dinner between Trump and Xi was cordial, with observers saying despite intense speculation prior to the encounter, both sides will make it work for their domestic audiences. "These types of summit are about pageantry. The Chinese are looking to get the right photo ops to show that President Xi is an equal to Donald Trump and that China is a superpower. At the same time, Donald Trump is looking to have a successful summit," said Harry Kazianis, defense studies director at the Center for National Interest. With the attack on Syria, Trump was also taking the opportunity to send a message out to Americans that as a strong leader, he is not like predecessor Barack Obama, analysts said. While there is talk that the Chinese may limit photo opportunities for fear that the impulsive Trump may embarrass Xi, there's little to worry about as both leaders would want to score points with their constituents, Kazianis added. The U.S. president is battling troubles with overhauling Obamacare and with his Supreme Court nominee, while China is preparing for a leadership reshuffle in the fall. "For both sides, they are going to want a successful summit and that is what we're going to see," Kazianis said. Trump and Xi are expected to discuss finer points of trade and foreign policy on Friday, finishing the event with a working lunch—but don't expect a major breakthrough over just two days, he added.

"The best outcome would be something that makes Donald Trump look good, even look good to himself, and that makes President Xi Jinping look good to the people watching in China. it's a optical matter rather than a substantive matter," said former U.S.-China Business Council President, Robert A. Kapp. While it was a strong possibility the two sides will agree on issues that will not be discussed in public, it would also be a negative if there was a failure to talk about any of issues on the meeting agenda, he added. "If they came up with something saying 'we had a frank and honest exchange of views, the end', that would be a pretty dark outcome," said Kapp. After all, the U.S. views rising China as a strategic competitor. "One of the reasons why this summit is so important and it needs to go on very well is that both sides have so many pressure points between them whether it's about the South China Sea, Taiwan, East China Sea, North Korea and now trade. This is a relationship that both sides want to get right and it's important to really see what compromises and strategies both sides are going to employ," said Kazianis.