WASHINGTON – President Trump expressed frustration with China in a tweet Wednesday, suggesting the U.S. might not work with the country to curb escalating nuclear tensions with North Korea – and issued a blanket warning about renegotiating trade deals as he prepared to depart for a global summit in Europe.

"Trade between China and North Korea grew almost 40% in the first quarter," Trump said in one post headed overseas for his second foreign trip as president. "So much for China working with us - but we had to give it a try!"

The tweet came in the wake of a North Korean test of an intercontinental missile could conceivably reach the United States.

In a separate social media missive earlier this week, Trump urged China to "put a heavy move on North Korea and end this nonsense once and for all!"

Earlier this year, Trump had asked Chinese president Xi Jinping to help rein in North Korean leader Kim Jong-Un and his nuclear weapons program, but Wednesday's tweet appears he may now be giving up on that idea. The U.S. president has vowed to go it alone against North Korea if necessary, but his options are few and feature many risks.

Trump is scheduled to meet with Xi at this week's G-20 summit in Hamburg, Germany.

The president left early Wednesday for a stop in Poland before heading on to the summit.

Another Wednesday tweet, this one devoted to trade, appeared to be aimed at China, Germany, and other G-20 members involved in trade disputes with the Trump administrations.

"The United States made some of the worst Trade Deals in world history," Trump said. "Why should we continue these deals with countries that do not help us?"

While Trump did not specifically identify any country, his aides have discussed tariffs ranging from Chinese steel to German cars.