China has lodged "stern representations" with the United States over a US navy vessel sailing through the disputed South China Sea, as US officials joined trade talks in Beijing to seek a de-escalation in the Sino-US trade war.
Asked about the timing of the operation during trade talks, Lu said resolving issues would benefit the two countries and the world.
A member of the USA delegation said the two sides would resume talks on Wednesday as they continue their first face-to-face meetings since Trump and Chinese President Xi Jinping agreed to a tariff truce during a meeting in Argentina on December 1.
Since the two presidents met on December 1, China has made a number of concessions to US demands, including temporarily cutting punitive tariffs on USA -made cars, resuming soybean purchases, promising to open up its markets for more foreign investment, and drafting a law to prevent forced technology transfers.
The American side is led by a deputy USA trade representative, Jeffrey D. Gerrish, according to the US government.
USA negotiators are headed into talks with Chinese counterparts as the two countries seek a deal to end a trade war that has raised fears of global economic turmoil.
"We urge the USA to immediately stop such provocative actions", Chinese foreign ministry spokesman Lu Kang told a regular press briefing, adding that Beijing had lodged a diplomatic complaint with Washington.
U.S. President Donald Trump, in a post on Twitter from Washington on Tuesday, reiterated his recent statement that the talk with China were going well but gave no other details.
After three days of negotiations, talks between the two sides in Beijing have just concluded - and there's real optimism of a breakthrough. "China has the good faith, on the basis of mutual respect and equality, to resolve the bilateral trade frictions".
Hundreds of billions in levies.
"As for whether the Chinese economy is good or not, I have already explained this".
Beijing and Washington have raised tariffs on billions of dollars of each other's goods, prompting fears the conflict will dampen global economic growth that is showing signs of slowing.
It was unclear if the ruckus over the warship might disrupt the working level talks being held at the Chinese Commerce Ministry. "China's development has ample tenacity and huge potential", Lu said.
"On whether this operation will affect the ongoing trade talks between the two sides, I believe proper resolution of trade disputes is conducive to the world".
China claims nearly all of the strategic South China Sea and frequently lambastes the United States and its allies over naval operations near Chinese-occupied islands.
Liu's appearance at the talks is a "symbol of Xi's personal buy-in" in the effort to reach a deal, said Leland Miller, chief executive officer of China Beige Book, a data-analytics firm that surveys companies across the Chinese economy. That meeting would likely include a senior Chinese government official along with trade Representative Robert Lighthizer and Treasury Secretary Steven Mnuchin.