President Donald Trump on Wednesday threatened to abandon working with China to address North Korea’s nuclear arms and long-range missile programs.

In a tweet posted just a few days before he will meet with Chinese President Xi Jinping at a G20 summit in Germany, Trump criticized China for increasing its trade with Pyongyang.

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Trump tweeted that China-North Korea trade grew by 40 percent in the first quarter of 2017. The American leader took his assessment of that uptick to Twitter: “So much for China working with us – but we had to give it a try!”

Trade between China and North Korea grew almost 40% in the first quarter. So much for China working with us – but we had to give it a try!

— Donald J. Trump (@realDonaldTrump) July 5, 2017

Trump responded to reporters’ questions about North Korea on Wednesday, minutes after firing off the tweet, saying as he walked toward Marine One to depart for his European trip: “We’re going to do very well.”

After the U.S. and Chinese presidents met at the White House and then Trump’s Florida resort in April, Xi vowed to lean more forcefully on the North Korean government to alter its behavior. But Pyongyang has moved ahead with its programs, including conducting its first successful test of an intercontinental ballistic missile on Tuesday.

Standing beside his South Korean counterpart in the White House Rose Garden on Friday, Trump declared that “the era of strategic patience” in regard to North Korea’s missile and nuclear arms programs was “over.”

He called on South Korea and other countries in the region to enact new sanctions against Pyongyang. But he also rattled his saber a bit, saying the U.S. will “always defend itself” and its allies.

Trump’s patience with China has grown thin in recent weeks.

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In a June 20 tweet, Trump said China’s attempts to alter North Korea’s behavior has “not worked.”

Trump, however, has not stated what he is prepared to do or is considering.

White House Press Secretary Sean Spicer has said in recent weeks that the Trump administration would continue to lean on China to influence Pyongyang.

The Wednesday morning tweet could be Trump’s attempt to pressure Xi to do more. Over the Fourth of July holiday, the president also appeared to try to do the same with Japan and South Korea, posting that it is “hard to believe” those two governments “will put up with this much longer.”

North Korea has just launched another missile. Does this guy have anything better to do with his life? Hard to believe that South Korea…..

— Donald J. Trump (@realDonaldTrump) July 4, 2017

….and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!

— Donald J. Trump (@realDonaldTrump) July 4, 2017