US President Donald Trump has welcomed Chinese President Xi Jinping to his Florida resort for their first summit.
Mr Trump said the two men had "developed a friendship" as they sat for dinner at his Mar-a-Lago retreat.
The American leader is expected to press his counterpart for action on North Korea, and Mr Xi to seek assurances on Taiwan.
Mr Trump has said the summit "will be a very difficult one". Last year he accused China of "raping the US".
During the election campaign, he said massive trade deficits and job losses could no longer be tolerated. But at dinner on Thursday, it was all smiles, with the leaders' two wives, folk singer Peng Liyuan and First Lady Melania Trump also in attendance.
The meeting was, however, largely overshadowed later by a US airstrike on an airbase in Syria in response to a suspected chemical weapons attack.
All eyes will be on the body language between the two leaders - one a softly spoken Communist Party apparatchik and the other a brash Manhattan property tycoon.
Despite his tough campaign talk, Mr Trump has so far not followed through on his threat to formally brand China a "currency manipulator", nor to hit Chinese imports with punitive tariffs.
The Republican president's blue-collar supporters will hope he can translate his China-bashing election rhetoric into concrete gains for American manufacturing workers.
One of the most urgent issues for the US is North Korea, which is trying to develop an intercontinental ballistic missile capable of hitting the west coast of the US with a nuclear device.
It fired a medium-range missile into the Sea of Japan on Wednesday, the latest in a series of launches.
Although Beijing has condemned this and previous missile tests, it has so far been reluctant to isolate its neighbour, fearing its collapse could spawn a refugee crisis and bring the US military to its doorstep.
Mr Trump is expected to call on Mr Xi to arm-twist North Korea into halting its nuclear programme by denying it access to banking institutions.
The US president told the Financial Times this week he was prepared to act unilaterally, saying: "If China is not going to solve North Korea, we will."
A senior White House official said Pyongyang would be a key test for the Trump-Xi relationship.
"The clock is very, very quickly running out," the official said. "All options are on the table for us."
For his part, Mr Xi will seek assurances from Mr Trump on US arms sales to Taiwan, which China considers a breakaway province that must eventually reunify with the mainland.
Mr Trump outraged China in December when he took the unorthodox step of accepting a phone call from the Taiwanese president.
But the US president later agreed to respect the "one China" policy in a telephone call with President Xi in February.
Climate change, which Mr Trump once dismissed as a Chinese hoax, and Beijing's building of artificial islands in the disputed South China Sea, could also come up.
Some protesters lined the streets on Thursday to voice their opposition to China's policy in the South China Sea.
Mr Xi's visit will conclude with a working lunch on Friday.
But there is unlikely to be any golf on the agenda. While Mr Trump is fond of hitting the fairway, Mr Xi's administration has cracked down on the sport in an anti-corruption drive.