U.S. Treasury Secretary Steven Mnuchin said Tuesday he had “begun to have very high-level conversations” on the Trans-Pacific Partnership, and rejoining the regional trade pact is an option for President Donald Trump.

Trump repeatedly attacked the TPP deal on the campaign trail and pulled the U.S. out of it soon after he took over early last year. However, last month he expressed openness to rejoining if the terms were improved. Mnuchin told the U.S. Chamber of Commerce in Washington that this was significant.

“He’s willing to negotiate,” Mnuchin said. “Whether we do multilaterals or we consider going back into TPP, again that’s something that’s on the table.”

Japan has spearheaded a drive to keep the pact alive among the remaining 11 members, and the resulting agreement is set to be signed on March 8. Mnuchin said the U.S. would focus on bilateral deals first before reviewing its stance on the TPP.

“It’s not a priority at the moment, but it is something the president will consider,” he added.

Japan has repeatedly said it’s not interested in renegotiation, and any such request would probably not be welcomed by other nations. The U.S. should rejoin the treaty as it is, President Michelle Bachelet of Chile told the Nikkei newspaper in an interview this week. Bachelet will host the signing ceremony for the treaty in March.

Still, Japan’s former TPP Minister Akira Amari said in an interview Tuesday that it might be feasible to add new clauses on topics not currently covered if U.S. concerns cannot be addressed outside the TPP framework.

He warned that by spurning the agreement, the U.S. risks allowing China to make global rules on trade and investment.

“China is trying very hard to get its own rules recognized as the standard,” Amari said. China’s rules are “a bit different from what Japan, the U.S. and Europe see as fair,” he added. “I don’t think the U.S. can accept China’s local rules becoming the global standard.”

Meanwhile, a lawmaker in Thailand said the military government is debating whether to join the pact, whose current members account for about 13 percent of the global economy. Indonesia, the Philippines, South Korea, Taiwan and the U.K. have also expressed interest in joining. Current members include Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam.