US President Donald Trump informed his Chinese counterpart, Xi Jinping, that one of his cabinet’s most strident trade hawks will lead negotiations aimed at averting a tariff escalation, according to reports on Monday.

Trump said that US Trade Representative Robert Lighthizer would spearhead talks as part of a framework agreement that was announced following the bilateral dinner meeting held at the Group of Twenty summit on Saturday, The Wall Street Journal reported, citing sources familiar with the matter.

The sources said the Chinese were surprised by the decision, having dealt mainly with Treasury Secretary Steven Mnuchin on trade issues in the past.

Lighthizer is seen as a hard-liner who is seeking to force major changes to China’s domestic industrial policy and impose steep tariffs if Beijing refuses to do so.

When asked about the report by reporters on Monday, White House economic advisor Larry Kudlow played down Lighthizer’s role.

“I’m sure he will be deeply involved,” Kudlow said on a call with reporters.

But, he added, “I’m sure secretary Mnuchin will be deeply involved as well.”

Lighthizer, he said, “will be in charge of enforcement, timelines…”

Kudlow was adamant, however, that China would have to move quickly with concessions that they had promised, including what he understood to be a pledge to lower tariffs on cars.

“They cannot slow walk this,” Kudlow said.