President Trump has had plenty of harsh words for foreign rivals recently. He’s threatened to raise tariffs on China, his administration has floated military action in Venezuela and announced the deployment of aircraft carriers off the coast of Iran. Noticeably absent from this list of tough talking diplomacy, however, is North Korea.

And it’s not as if Trump didn’t have anything to worry about. On Saturday, North Korean dictator Kim Jong Un oversaw the launch of what seems to have been a short-range ballistic missile. Instead of condemning the launch, Trump oddly tweeted support for Kim saying that Kim won’t interfere with a deal and that “He also knows that I am with him & does not want to break his promise to me.”

Anything in this very interesting world is possible, but I believe that Kim Jong Un fully realizes the great economic potential of North Korea, & will do nothing to interfere or end it. He also knows that I am with him & does not want to break his promise to me. Deal will happen! — Donald J. Trump (@realDonaldTrump) May 4, 2019

Despite the significance of the launch and Kim’s clear efforts to test the waters of what the United States will tolerate, the response from both the U.S. and South Korea reflected the muted tone of Trump’s tweet. Secretary of State Mike Pompeo even tried to brush it off explaining that the missile was “relatively short range.”

Pompeo isn’t wrong to cite the weapon as less serious than, say, an intercontinental ballistic missile, but that doesn’t mean it isn’t dangerous. With a range of a few hundred miles, a short-range missile could easily hit Seoul threatening civilians and the more than 20,000 troops stationed there.

The idea behind keeping quiet seems to be that by sparing North Korea a diplomatic penalty, the U.S. might keep Kim at the negotiating table. That's a laudable goal, but the prospect of actually reaching an agreement seems less and less realistic.

The missile launch on May 4, along with an earlier test of short range weapons in April, likely designed to combat tanks, signal that far from an interest in building good will with the U.S., Kim wants to showcase his power.

That means that instead of jumping from these successful military demonstrations to a new round of talks with Washington, Kim might instead go for yet another launch. By not pushing back on Kim now, however gently and diplomatically, the U.S. is risking giving Kim the green light for more dangerous behavior.

After talks between President Trump and Kim failed earlier this year in Vietnam, both sides seemed interested in continuing to work towards a deal, even if the hope for an agreement in Hanoi was premature. Now that Kim has upped the stakes and dropped his conciliatory approach to Washington, it's Trump's move. How he plays his hand will determine if the diplomacy stays on the radar or the U.S. simply goes back to viewing North Korea as a threat. Either way, Trump should tread carefully and recognize that turning a blind eye toward aggressive moves from Pyongyang will neither deter further aggression nor push Kim toward an agreement.