The Trump administration continued to raise the temperature in trade tensions with China on Monday, with top trade official Robert Lighthizer confirming a Twitter threat of increased tariffs as official policy.

“We felt like we were on track to get somewhere, but over the course of the last week or so we have seen an erosion in commitments by China,” Lighthizer told reporters on Monday.

“That, in our view, is unacceptable,” he added.

The Chinese side, he said, was “retreating from specific commitments that had already been made in our judgment … These were substantial, not minor ones.”

In his view, Lighthizer said, “these were serious, real commitments that were enforceable and that some people in China objected to that.”

Treasury Secretary Steven Mnuchin also chimed in, concurring that China had backtracked on specific commitments.

As of Monday evening, EST, Beijing had not yet released an official statement as to whether Vice-Premier Liu He would travel to Washington this week to lead trade talks. Liu was scheduled to come and top US officials suggested his trip was still on track. There was speculation that China was considering canceling his visit after the US on Sunday threatened to increase tariffs.

Global equities markets plunged on Monday following Tweets from the US president that he would substantially raise tariffs on imported Chinese goods.

US stocks recovered most of their losses amid speculation that the tweets were bluster, but US stock futures turned lower following confirmation that the US side would increase tariffs.