U.S. President Donald Trump denounced China's trade with North Korea on Wednesday and cast doubt on whether Beijing is working with Washington to counter the North Korean nuclear threat.

"Trade between China and North Korea grew almost 40 pct in the first quarter. So much for China working with us - but we had to give it a try!" Trump said in a Twitter post.

Even before Pyongyang said on Tuesday it successfully test-launched an intercontinental ballistic missile, Trump has recently suggested he was running out of patience with China's modest steps to pressure North Korea and has been considering moving ahead on trade actions.

Analysts said the latest missile could put all of the U.S. state of Alaska in range for the first time.

Trump posted the tweet shortly before leaving for Warsaw on his way to a G20 summit in Germany on Friday and Saturday.

During that summit, he will meet for the second time with Chinese President Xi Jinping, with whom he has expressed frustration for failing to use enough leverage to curb North Korea's nuclear program.

China is North Korea's largest trading partner and ally.

Data released in April by Beijing showed China's trade with North Korea grew 37.4 percent in the first quarter this year from the same period in 2016, according to reports in the New York Times and Financial Times. Chinese exports surged 54.5 percent and imports increased 18.4 percent, according to the General Administration of Customs.