Threats to launch nuclear strikes and warnings of “nuclear holocaust” have become common since the country’s latest nuclear test, its third, in February. Although North Korea is believed to have a small nuclear weapons arsenal, most analysts doubt it could follow through on threats to deliver them to the United States by missile.

One American intelligence agency recently said it had “moderate confidence” that the North had mastered the technology of building a weapon that could fit on a missile warhead, but the Obama administration said that was not the consensus among the United States’ 15 other intelligence agencies. Most analysts believe that Kim Jong-un, the North’s leader, is using the nuclear bluster to consolidate the support of his people and bolster his leverage in dealing with Washington and its allies.

The threatening statements come after days of relative quiet that followed weeks of warnings of dire consequences if the United States and South Korea provoked the North. Mr. Kim’s government was already angered by United Nations sanctions punishing it for the nuclear test in February and by particularly robust joint exercises by the American and South Korea militaries.

The timing of the latest threats appeared to be tied to the military anniversary. North Korea’s military, the backbone of Mr. Kim’s dynastic rule, has traditionally used the date to swear its loyalty to the Kim family and vent its anti-American vitriol.

During the military ceremony on Thursday, Mr. Kim saluted columns of soldiers marching past, and airplanes made demonstration flights, the North Korean news agency said.