Tensions between the two sides of the peninsula have escalated since May when the North began flying balloons carrying garbage across the border to the South, prompting Seoul to respond by restarting loudspeaker propaganda broadcasts.

This week, North Korea accused South Korea of flying drones over Pyongyang on three occasions this month and threatened to respond with force if it happened again.

North Korean State news agency KCNA said on Saturday that a crashed South Korean military drone had landed in North Korean territory, Reuters reported.

KCNA released photos showing what looked like a damaged aircraft with wide, V-shaped wings and winglets and said a probe had concluded it was the same type of drone that appeared in a South Korean military parade earlier this month. This was reported by The Associated Press, who also noted that South Korea’s defense ministry’s initial “vague denial” was adjusted hours later to say that it couldn’t confirm whether or not the North’s claims were true.

South Korean lawmaker Yu Yong-weon told Reuters the drones in Pyongyang’s photos looked like surveillance drones made by Sungwoo Engineering and supplied to the South Korean military in 2023.

KCNA said that if any “violation of the DPRK’s (North Korean) territorial ground, air and waters by ROK’s (South Korean) military means is discovered and confirmed again, it will be regarded as a grave military provocation against the sovereignty of the DPRK.”

This meant that “a declaration of war and an immediate retaliatory attack will be launched,” KCNA said.

However, South Korea’s Defense Ministry, which Newsweek has contacted for comment, said that Pyongyang’s “one-sided claims are not worth verifying, nor do they merit a response,” according to Reuters.

The news agency reported that Seoul had not said if either its military or any civilians were responsible for the purported drones. Seoul said that any comment to Pyongyang’s claim would be to get involved in a ploy, the agency added.

Tensions on the Korean Peninsula are now at their worst in years and on Monday, Seoul summoned the Russian ambassador to protest deepening military cooperation between Pyongyang and Moscow.

South Korea’s spy agency had said North Korea sent special operation forces to support Vladimir Putin’s war against Ukraine and there are reports that some of these troops had been captured in Russia’s Kursk region.

NATO chief Mark Rutte said Monday that sending North Korean soldiers to provide support to Russia in Ukraine would be “a significant escalation.”

It comes amid a report that Seoul might dispatch experts to Ukraine to help Kyiv’s forces with information on the tactics and doctrine of the North Korean army,” South Korean outlet Newspim said, according to a translation.

Earlier this month, North Korean leader Kim Jong Un again warned he could use nuclear weapons in potential conflicts with South Korea and the U.S as he accused the countries of beefing up their military alliance.

This includes the South Korea-U.S. deterrence guideline signed in July to integrate South Korean conventional capabilities with U.S. nuclear weapons to deal with Pyongyang’s repeated nuclear threats.

The U.S. has around 28,500 soldiers stationed in South Korea. A report by the Chicago Council on Global Affairs shared with Newsweek this week found that over half of Americans (51 percent) back using American forces troops to defend South Korea if North Korea invaded.

It also found that 43 percent of Americans backed accepting North Korea as a nuclear state and entering arms control discussions with Pyongyang’s leadership.