The summit was also watched closely as to whether the U.S. stands up to China for bullying South Korea for hosting the U.S. THAAD missile defense system created to defend better against ever-growing missile threats from North Korea.
Tillerson said Trump and Xi noted the urgency of the threat of North Korea's weapons program and that they reaffirmed their commitment to a denuclearization of the divided Korean Peninsula.
President Donald Trump and his Chinese counterpart Xi Jinping wrapped up their first summit by announcing a 100-day plan to improve strained trade ties, the only tangible announcement after their meetings that were overshadowed by the U.S. military strikes in Syria.
He did not elaborate on the progress or the problems. During his presidential campaign, Trump fiercely condemned current trade practices, stoking fears of a US-China trade war.
Trump and Xi agreed to increase cooperation and work with the worldwide community to convince North Korea to peacefully resolve the issue and dismantle its illegal nuclear and missile programmes, Spicer said, adding that the two sides had a candid discussion on regional and maritime security. That's about all they appear to have accomplished after about 18 hours together at Trump's Mar-a-Lago resort - a visit interrupted by a US cruise-missile strike on Syria during dinner.
But the surprise US military response to Syrian President Bashar al-Assad's apparent chemical weapons attack on civilians threw a wild card into the summit.
China has sided with Russian Federation at the United Nations in opposing condemnation of Mr Assad's government but has not become directly involved in the conflict.
But at a briefing in Beijing on Friday, Chinese Foreign Ministry spokeswoman Hua Chunying offered only a muted comment. Xi said a few words afterward in Chinese, but no translator was present.
"I suspect Xi will treat Trump's threat against North Korea as more serious than before this, provided the behind the scenes body language does not counteract it", Douglas H. Paal, vice president for studies at the Carnegie Endowment for International Peace, told The New York Times. Along with its rapidly advancing nuclear and long-range missile capabilities, it has its artillery and short-range missiles trained on Seoul, the capital of USA ally South Korea and a city of more than 10 million people.
Michael Auslin from the conservative American Enterprise Institute has said that US presidents should not try using a personal touch with China. And some experts suggest the timing of the strikes was meant to put more pressure on China regarding its relationship with North Korea.
Speaking after meeting with Chinese President Xi Jinping, Trump said the leaders share an "outstanding" relationship.
The attack was made public on Thursday evening just moments after Mr Xi and his wife left the resort following dinner. Senior White House officials say the president intends to have a frank but productive conversation with President Xi about how the U.S.is getting the short end of the stick.
While Trump would not say what he wants China to do specifically, he suggested there was a link between "terrible" trade agreements the US has made with China and Pyongyang's provocations.
Trump said in an interview with the Financial Times published Sunday that China should help with the problem by using the "great influence" it has over Pyongyang, warning that if it doesn't, the USA will solve the problem on its own, and that "won't be good for anyone".
State-run Chinese tabloid Global Times said the meeting "served as an indicator that the China-U.S. relationship is still very much on course since the Trump administration took office in January" and it was likely the two nations would develop a more "pragmatic relationship".
In return, Xi hoped to obtain assurances from Trump on punitive tariffs and the delay of an American arms sale to Taiwan, at least until after a major Communist Party meeting later this year. Trump strongly criticized China's trade policies and trade surplus over the United States throughout the presidential campaign and into the early days of his presidency, going so far as to sign an executive order to investigate the trade deficit with China last month.
China and the United States are now each other's biggest trading partner, from which the two peoples benefit a lot, Xinhua news agency quoted Xi as saying.
"The reality is that our decision to strengthen our military power to respond to attacks of force is the right choice", the statement said.
"I think China will be stepping up", Trump told reporters on Thursday.