In one of Russia’s largest aerial assaults against Ukraine since the start of the war, Belarus claimed on Thursday that it had shot down a Ukrainian S-300 air defense missile in a field. Belarus then protested to the ambassador of Ukraine about the incident.

In a video uploaded to social media by the state-run BelTA news agency, the military commissar of the Brest region, Oleg Konovalov, downplayed the incident, claiming people had “There is nothing to be concerned about. Sadly, these things do occur “.

He compared the incident to one in November, when an S-300 believed to have strayed after being fired by Ukrainian air defences landed on the territory of NATO-member Poland, triggering fears of an escalation that were rapidly defused.

Nevertheless, the Ukrainian ambassador was summoned to the foreign ministry in Minsk to receive a formal protest.

“The Belarussian side views this incident as extremely serious,” spokesperson Anatoly Glaz said.

“We demanded that the Ukrainian side conduct a thorough investigation, … hold those responsible to account and take comprehensive measures to prevent the recurrence of such incidents in the future.”

A Ukrainian military spokesman in effect acknowledged that the missile was a Ukrainian stray, saying the incident was “nothing strange, a result of air defence” and something that “has happened more than once”.

The S-300 is a Soviet-era air defence system used by both Russia and Ukraine.

Belarus said the missile had come down near the village of Harbacha in the Brest region, some 15 kms (9 miles) from the border with Ukraine, at around 10 a.m. (0700 GMT).

“Fragments were found in an agricultural field … the wreckage belongs to an S-300 anti-aircraft guided missile fired from the territory of Ukraine,” the defense ministry said.

The incident occurred as Russia was launching its latest wave of missile attacks on cities across Ukraine.

Photos and video said to show S-300 missile parts laying in a field were uploaded by BelTA.

In February, Belarus permitted Moscow to utilize its territory as a jumping-off point for the invasion of Ukraine, and in recent months, there has been an increasing flurry of Russian and Belarusian military action in Belarus.

However, Minsk has stated that it is not a party to the conflict and would not become one unless Ukraine or Ukraine’s Western allies pose a threat to their own security.

While Russia appears to be using repurposed S-300 missiles to attack ground targets, Ukraine has employed the S-300 system to intercept incoming Russian missiles.