Speculation had mounted that Pyongyang could carry out a sixth nuclear test or another missile launch to mark 85 years since the founding of its army.
But no such event — which usually happens in the morning — had taken place by noon, and Seoul’s defence ministry said “no unusual development had been detected”.
Instead the South’s Yonhap news agency cited an unnamed government source saying Pyongyang marked the anniversary with its “largest ever firing drill”, carried out in the eastern port city of Wonsan and presumed to have been overseen by leader Kim Jong-Un.
North Korea has ambitions to build a missile capable of reaching the US mainland and tensions have soared in recent months as it carried out a string of missile tests that sparked tit-for-tat sabre-rattling between it and Washington.
This image made from North Korea’s KRT news on shows the military anniversary celebartions.KRT
Pyongyang’s rhetoric always intensifies in the spring, when Seoul and Washington hold joint military drills it sees as rehearsals for an invasion.
The North’s Rodong Sinmun – the official mouthpiece of the ruling Workers’ Party of Korea – warned Tuesday of dire consequences in the event of a US-led pre-emptive strike.
It promised “the most brutal punishment… in the sky and land as well as at sea and from underwater without any warning or prior notice”.
Watch: North Koreans mark the military anniversary
North Korea launched two missile tests this month while US President Donald Trump and his senior aides have warned that “all options are on the table” against Pyongyang, including military action.
WATCH: North Korea denounces US for UN meeting
Trump on Monday urged the UN Security Council to consider stronger sanctions against Pyongyang, and US senators will be briefed on North Korea at the White House on Wednesday.
Washington has sent the nuclear-powered aircraft carrier USS Carl Vinson to the Korean peninsula, where it is expected to arrive — after a derision-provoking delay — later this week.
Watch: Trump says UN must ready new sanctions for North Korea
The vessel will take part in joint naval drills with the South’s forces to “demonstrate Seoul and Washington’s strong determination to punish North Korean provocations”, the South Korean Navy said in a statement.
They will take place in the East Sea, the South’s name for the Sea of Japan, it said, and the two allies will also begin joint naval exercises in the West Sea on Tuesday “in relation to the current security situation”.
The nuclear-powered US submarine USS Michigan also made a port call to the South’s Busan on Tuesday in another show of force.
Trump has said the US was sending an “armada” to the Korean peninsula, including submarines.
Watch: Bishop says North Korea is a threat
The USS Michigan is built to carry submarine-launched ballistic missiles and Tomahawk cruise missiles capable of making precision strikes against the North’s nuclear facilities, Yonhap said.
But the South Korean Navy called the vessel’s visit “routine”, adding it would not take part in any joint exercises.