North Korean state media released photos Sunday confirming projectile testing that South Korea reported the day before.
The photos show North Korean leader Kim Jong-un watching live-fire drills of long-range, multi-rocket launchers and what appears to be a ballistic missile. In one photo, he points at a monitor showing a weapon landing in the sea between North Korea and Japan.
In an accompanying report, Kim said the country's military strengthening needs to be more persistent to protect its political sovereignty and economic independence.
This latest announcement, along with a reported test a few weeks ago, signals an escalation of tensions between the U.S. and North Korea since Kim and President Donald Trump met in February.
The two sides have been at odds since the summit failed to come to an agreement on denuclearization. In late April, North Korean state media said Kim warned the situation "may return to its original state as the U.S. took a unilateral attitude in bad faith."
Still, the U.S. remains publicly optimistic. On Saturday, President Trump said Kim "does not want to break his promise" to the U.S. And Secretary of State Mike Pompeo told ABC News on Sunday he believes "there's an opportunity to get a negotiated outcome, where we get fully verified denuclearization."