On Saturday, North Korea launched a barrage of projectiles off its east coast, including what it claimed were newly developed “tactical guided weapons” in an apparent show of Pyongyang’s frustration over the stalled nuclear talks. Pyongyang said later that they were “routine” and “self-defensive” drills that were not intended as provocations. South Korea and the United States had steered clear of outright condemnation in an apparent effort to keep the negotiating process with Pyongyang alive. They, however, appear to be getting concerned after the North’s latest missile launch.

Hours after the Thursday missile launch, President Moon Jae-in said in a TV interview that the North’s missile launches, even if they are short-range ones, could be a violation of U.N. Security Council resolutions if they are ballistic missiles. U.S. President Donald Trump said that Washington is monitoring North Korea “very seriously,” adding he doesn’t think the regime is ready to negotiate. After the North fired projectiles last week, he expressed confidence in leader Kim that he will keep his promise on denuclearization. North Korea last conducted a ballistic missile test in November 2017. Trump has touted the lull in the North’s missile and nuclear provocations as one of his biggest achievements in talks with Pyongyang.

Nuclear negotiations have been stalled since the second summit held in February between Kim and Trump fell apart as they failed to find common ground over Pyongyang’s denuclearization steps and Washington’s sanctions relief. Pyongyang wanted major sanctions relief as it is pushing to rebuild its economy. Washington remained firm in keeping sanctions in place until the North completely gives up its nuclear weapons. Last month, leader Kim urged Washington to change its hard-line stance on denuclearization talks, saying he will wait for its “bold decision” until the end of this year. The Choson Sinbon, a pro-North Korea newspaper, warned on Thursday that a “nuclear confrontation” could flare up again if the U.S. misses the opportunity for negotiations with Pyongyang. Thursday’s missile launches took place while the U.S. Special Representative for North Korea Stephen Biegun is visiting South Korea to discuss cooperation on North Korea’s denuclearization.

They also occurred as Seoul and Washington are considering provisions of food aid to the impoverished state reportedly suffering acute food shortages aggravated by global sanctions and years of droughts and floods. Experts say that food assistance to North Korea could serve as a catalyst in bolstering cross-border exchanges and move stagnant inter-Korean relations forward, but critics oppose it, saying there should be no reward for its bad behavior, such as the missile launches.