President Donald Trump canceled Secretary of State Michael Pompeo’s trip to North Korea just one day after it was announced, citing a lack of “sufficient progress” in talks aimed at denuclearizing the Korean peninsula.

Trump, in a series of tweets Friday, said that Pompeo will likely return to North Korea after America’s trading disputes with China are resolved. The move may be aimed at trying to persuade China to continue enforcing a sanctions regime against North Korea that has showed signs of weakening, in return for the larger benefit of improved trade ties with the U.S.

Yet the reversal was surprising given that Trump’s announcement came just one day after Pompeo tapped a former Ford Motor Co. executive, Steve Biegun, to lead talks with North Korea. Biegun and Pompeo were supposed to depart for Pyongyang as early as this weekend.

The yen strengthened against the dollar on Trump’s announcement before paring gains.

Pompeo has sought to shore up support for tough United Nations sanctions on North Korea until there’s “verifiable” progress on denuclearization by Kim Jong Un’s regime following the historic summit between Kim and Trump in June. Although North Korea recently delivered what it said were U.S. remains from the Korean War to the U.S. for examination and identification, the regime criticized Pompeo’s stance on his last two visits to Pyongyang as “gangster-like” and too focused on the nuclear issue.

Despite the lack of concrete results on the nuclear front, U.S. ally South Korea has moved to improve ties, announcing this week that it would set up a liaison office at an industrial park it sponsors in North Korea. That followed a set of reunions this week between families separated by the 1950-53 Korean War.

But beyond denuclearization, Trump signaled his frustration with stalled trade talks with China. The U.S. has leaned heavily on China to help enforce a tougher sanctions regime imposed last year because they are North Korea’s largest trading partner and share a border with the isolated regime in Pyongyang.

Trade Dispute

“Additionally, because of our much tougher Trading stance with China, I do not believe they are helping with the process of denuclearization as they once were (despite the UN Sanctions which are in place),” Trump said Friday on Twitter.

The trade war between the U.S. and China is primed to escalate further after their governments failed to make progress in two days of talks this week. The two sides had met with low expectations for the meetings and no further talks had been scheduled, a person familiar with the discussions said.

Trump also signaled that he does expect high-level talks with North Korea to resume soon and he sought to downplay the idea that his decision might be seen as a snub of Kim, who is says he’s forged a good working relationship with.

“Secretary Pompeo looks forward to going to North Korea in the near future, most likely after our Trading relationship with China is resolved. In the meantime I would like to send my warmest regards and respect to Chairman Kim. I look forward to seeing him soon!” Trump tweeted.