President Donald Trump said on Tuesday that trade talks between the United States and China were going well, though he warned that he would be "tougher" in negotiations if they dragged on until his second term.

"We are doing very well in our negotiations with China," Trump wrote in a post on Twitter, arguing that Beijing could ill afford to drag its feet in talks given the damage U.S. tariffs were inflicting on its economy.

Trump said if the United States and China did not resolve their trade dispute and he won re-election, "Deal would get MUCH TOUGHER! In the meantime, China's Supply Chain will crumble and businesses, jobs and money will be gone!"

He did not provide details about the negotiations or how they could become tougher.

Trump, a Republican, has often publicly repeated his belief that Beijing is trying to slow-walk trade negotiations in the hopes a victory by a Democratic presidential candidate in 2020 may lead to better terms in an agreement.

Washington began imposing 15% tariffs on an array of Chinese imports on Sunday, while China began placing new duties on U.S. crude oil.

China has since lodged a complaint against the United States at the World Trade Organization over U.S. import duties, its third lawsuit challenging Trump’s China-specific tariffs.

Chinese Vice Premier Liu He said earlier on Tuesday that China vehemently opposes a trade war.