The Stockholm meeting was an effort to resume denuclearization talks that had stalled since the collapse of the second summit meeting between Mr. Trump and North Korea’s leader, Kim Jong-un, in Hanoi, Vietnam, in February.
That meeting foundered on disagreements about how fast and how thoroughly the North should dismantle its nuclear program and how soon the United States would ease its sanctions.
Mr. Trump has played down the recent North Korean tests as “small ones” involving short-range ballistic missiles, although any test of ballistic missile technology by the North violates United Nations Security Council resolutions. The Pukguksong-3 launched early this month was considered a medium-range ballistic missile.
In a speech in April, Mr. Kim said he would wait only until the end of the year for Washington to come up with a more flexible proposal.
North Korea has since issued vague warnings that it might end a self-imposed moratorium on nuclear and intercontinental ballistic missile tests. Mr. Trump has cited that pause as one of his biggest gains in his on-again, off-again diplomacy with the North.
The launches Thursday came a day after Mr. Kim sent a letter of condolence to Mr. Moon over the death of his 92-year-old mother, who was born in what is now North Korea and fled south during the 1950-53 Korean War. The gesture had raised hopes for resuming dialogue between the Koreas.
In recent months, North Korea has heaped scorn and insults upon the South, accusing it of failing to implement economic cooperation that Mr. Kim and Mr. Moon agreed upon when they met in Pyongyang in September of last year. Last week, Mr. Kim ordered the demolition of South Korean hotels and other buildings in a resort complex that the two countries once operated together.
Motoko Rich contributed reporting from Tokyo.