President Donald Trump issued a positive message toward Xi Jinping on Friday morning, after a phone call with the Chinese president about the coronavirus.

“Great discipline is taking place in China, as President Xi strongly leads what will be a very successful operation,” Trump wrote on Twitter. “We are working closely with China to help!”

Trump confirmed his conversation with President Xi after reports from China noted the Chinese leader reassured President Trump in a phone call they could contain and defeat the virus that has killed nearly 640 people.

Trump praised Xi’s efforts.

“He is strong, sharp and powerfully focused on leading the counterattack on the Coronavirus,” Trump wrote.

President Xi spoke to Trump after the death of a Chinese whistleblower doctor who raised the alarm about the virus but was arrested by the Chinese government.

Trump expressed his belief that Xi would wipe out the virus, especially as the weather got warmer.

“Nothing is easy, but he will be successful, especially as the weather starts to warm and the virus hopefully becomes weaker and then gone,” he wrote.

Just had a long and very good conversation by phone with President Xi of China. He is strong, sharp and powerfully focused on leading the counterattack on the Coronavirus. He feels they are doing very well, even building hospitals in a matter of only days. Nothing is easy, but… — Donald J. Trump (@realDonaldTrump) February 7, 2020