US President Donald Trump has said he believes China's handling of the coronavirus is proof that Beijing "will do anything they can" to make him lose his re-election bid in November.
In an interview in the Oval Office, Mr Trump talked tough on China and said he was looking at different options in terms of consequences for Beijing over the virus.
Mr Trump has been heaping blame on China for a global pandemic that has killed at least 60,000 people in the US and thrown the economy into a deep recession, putting in jeopardy his hopes for another four-year term.
The Republican president, often accused of not acting early enough to prepare the US for the virus, said he believed China should have been telling the world about the coronavirus much sooner.
Asked whether he was considering the use of tariffs or even debt write-offs for China, Mr Trump would not offer specifics.
"There are many things I can do," he said. "We're looking for what happened."
China says it has no interest in meddling in the US election.
"China will do anything they can to have me lose this race," said Mr Trump.
He said he believes Beijing wants his Democratic opponent, Joe Biden, to prevail to ease the pressure he has placed on China over trade and other issues.
"They're constantly using public relations to try to make it like they're innocent parties," he said of Chinese officials.
He said the trade deal that he concluded with Chinese President Xi Jinping aimed at reducing chronic US trade deficits with China had been "upset very badly" by the economic fallout from the virus.
A senior Trump administration official, speaking on condition of anonymity, said that an informal "truce" in the war of words that Mr Trump and Mr Xi essentially agreed to in a phone call in late March now appeared to be over.
The two leaders had promised that their governments would do everything possible to co-operate to contain the coronavirus.
In recent days, Washington and Beijing have traded increasingly bitter recriminations over the origin of the virus and the response to it.
However, Mr Trump and his top aides, while stepping up their anti-China rhetoric, have stopped short of directly criticising Mr Xi, who the US president has repeatedly called his "friend".
Mr Trump also said South Korea has agreed to pay the US more money for a defence co-operation agreement but would not be drawn out on how much.
"We can make a deal. They want to make a deal," Mr Trump said. "They've agreed to pay a lot of money. They're paying a lot more money than they did when I got here [in January 2017]."
The US stations roughly 28,500 troops in South Korea, a legacy of the 1950-'53 Korean War that ended in an armistice, rather than a peace treaty.
Mr Trump is leading a triage effort to try to keep the US economy afloat through stimulus payments to individuals and companies while nudging state governors to carefully reopen their states as new infections decline.
He sounded wistful about the strong economy that he had enjoyed before the crisis, which has seen millions of people lose their jobs and the faltering of GDP.
"We were rocking before this happened. We had the greatest economy in history," he said.
He said he is happy with the way many governors are operating under current strain but said some need to improve.
There was some good coronavirus news in the US too, as Gilead Sciences Inc said its experimental antiviral drug remdesivir was showing progress in treating virus victims.
Mr Trump has also been seeking an accelerated timetable on development of a vaccine.
"I think things are moving along very nicely," he said.
At the end of the half-hour interview, Mr Trump offered lighthearted remarks about a newly released Navy video purportedly showing a UFO.
"I just wonder if it's real," he said. "That's a hell of a video."