State media said that Pyongyang will mark 70 years since the signing of the armistice, known as Victory Day in the North, in a "grand manner that will go down in history".

A large-scale military parade and other events are expected to be held this week to mark the anniversary, with satellite images indicating that soldiers and civilians have been training for the parade for months, Seoul-based specialist site NK News reported.

Leader Kim Jong Un's biggest nuclear-capable missiles and other military capabilities are likely to roll through Kim Il Sung Square during the event, it added.

Seoul's defence ministry said Tuesday it had detected more "people and equipment" in the capital Pyongyang, adding that South Korean and US intelligence agencies were closely monitoring the North's upcoming celebration.

The official Korean Central News Agency reported, and Beijing confirmed, that a Chinese delegation led by Politburo member Li Hongzhong would travel to the North for the event -- the first known visit by a foreign delegation since the start of the pandemic.

North Korea has been under a rigid self-imposed coronavirus blockade since early 2020 to protect itself from Covid-19, which has prevented even its own nationals from entering the country.

It only resumed some trade with China last year, and allowed Beijing's new envoy to take up his position earlier this year.

Beijing said the delegation would travel to Pyongyang on Wednesday, suggesting they would not be required to undergo an extensive quarantine ahead of the Thursday anniversary event.

An armistice agreement ending Korean War hostilities was signed on July 27, 1953 but the two Koreas remain technically at war because the agreement was never replaced by a peace treaty.

- China ties -

"It is expected that North Korea will try to reap the benefit of Beijing condoning its nuclear development by unveiling a new ICBM when a Chinese high-level delegation attends its large-scale military parade," Yang Moo-jin, president of the University of North Korean Studies in Seoul, told AFP.

"It seems that the intention is to show off the strengthening of solidarity between North Korea and China amidst the global political disruption caused by the ongoing US-China conflict."

He added that it could also be a sign that the border between the North and China might be reopened in the not too distant future.

Beijing is North Korea's most important ally and economic benefactor, their relationship forged in the bloodshed of the Korean War in the 1950s.

"North Korea has always touted its Korean War armistice anniversary as the day when North Korea and China fought together and won," North Korean defector and researcher An Chan-il told AFP.

"As Pyongyang needs Beijing's support as much as ever, it is expected that there will be the greatest hospitality ever for the Chinese delegation."

- More missiles -

North Korea fired two ballistic missiles late Monday, Seoul said, the latest in a series of weapons tests in recent weeks by Pyongyang, which come as Seoul and Washington ramp up defence cooperation.

Last week South Korea hosted a visit by a US nuclear-capable submarine, the first such deployment since 1981.

And in a move that likely further provoked the North, a second US submarine, the nuclear-powered USS Annapolis, arrived at a South Korean naval base Monday.

Relations between the two Koreas are currently at one of their lowest historical points, as diplomacy between Pyongyang and Seoul has stalled and Kim has called for ramping up weapons development, including tactical nukes.

Tensions have risen again recently due to US soldier Travis King, who was on a tour of the demilitarised zone last week when he ran across the border into North Korea.

The UN Command, a US-led multinational force that oversees the Korean War truce, said Monday it has begun discussions with Pyongyang over the American serviceman.