Pelosi, who visited Seoul earlier this week, became the highest-ranking US official to visit the Joint Security Area between the two Koreas since Donald Trump met North Korea's Kim Jong Un there in 2019.
North Korea has hit out at US House Speaker Nancy Pelosi over her recent visit to the heavily fortified Demilitarised Zone, calling her the "worst destroyer of international peace".
Pelosi, who visited Seoul earlier this week following a trip to Taiwan, became the highest-ranking US official to visit the Joint Security Area (JSA) between the two Koreas since then-president Donald Trump met North Korean leader Kim Jong Un there in 2019.
Prior to the JSA visit, Pelosi discussed the "grave situation" and growing threat posed by the North's nuclear weapons programme with her South Korean counterpart, National Assembly Speaker Kim Jin-pyo.
The pair called for "strong and extended deterrence against North Korea", and vowed to support efforts by Washington and Seoul to achieve Pyongyang's denuclearisation.
The North denounced on Saturday Pelosi for both her discussions with Kim and her visit to the JSA.
On top of the deterrence talks, Pelosi "made her appearance even in the joint security area of Panmunjom, utterly betraying the vision of the hostile policy of the current US administration towards the DPRK," said Jo Yong Sam, an official at North Korea's foreign ministry, using the North's official name.
"The US is just adding fuel to the fire," Jo added in a statement carried by Pyongyang's official Korean Central News Agency.
The JSA is the only spot along the tense, 250-kilometre (155-mile) frontier where soldiers from North Korea and the US-led United Nations Command stand face to face.
'US will have to pay'
Pelosi's Taiwan visit, meanwhile, drew threats and massive military drills from China, which sees the self-ruled island as a part of its territory and has vowed to take it, by force if necessary.
China is the North's key ally and trade partner, and Pyongyang also lashed out at Pelosi over the visit.
"Pelosi, the worst destroyer of international peace and stability... incurred the wrath of the Chinese people for her recent junket to Taiwan," the foreign ministry's Jo said in the statement.
"The US will have to pay dearly for all the sources of trouble spawned by her wherever she went."
The rebuke from the North comes about a week after Kim Jong Un said his country was "ready to mobilise" its nuclear deterrent in any future military conflict with the United States and Seoul.
North Korea has conducted a record-breaking blitz of weapons tests so far this year, including firing an intercontinental ballistic missile at full range for the first time since 2017.
Washington and Seoul officials have repeatedly warned that the North is preparing to carry out what would be its seventh nuclear test — a move that the United States warned would provoke a "swift and forceful" response.