Donald Trump plans to pull the U.S. out of the Trans-Pacific Partnership on his first day in office, putting the future of the sweeping trade deal in jeopardy.

He announced his plan to back out of the deal, which his presidential election opponent Hillary Clinton had also denounced, in a video message posted to Twitter.

The TPP was one of President Barack Obama’s most controversial foreign policy moves. The agreement aimed to promote free trade while putting pressure on countries faltering on human rights, but it was widely panned by green and labor rights groups. Critics say the deal favors major corporations and wouldn’t improve conditions for vulnerable workers in places like Vietnam and Malaysia.

.@transition2017 update and policy plans for the first 100 days. pic.twitter.com/HTgPXfPWeJ — Donald J. Trump (@realDonaldTrump) November 21, 2016

The irony of U.S. withdrawal from the TPP is that it could be seen as a big win for China, a country that Trump has spent countless hours attacking. As Time points out, China is not a part of the TPP and has instead backed a rival trade pact that doesn’t include the U.S.