Eight military servicemen were killed after their helicopter and fighter jet collided in severe weather in eastern Romania near the Black Sea, marking the deadliest day in recent years for air force incidents.

The European Union member is leading efforts to bolster NATO's eastern border as Russia pursues an all-out war in neighboring Ukraine and has just received international reinforcements.

The IAR 330 Puma helicopter crashed on Wednesday in Gura Dobrogei, 11 kilometers (seven miles) from the airstrip, the defense ministry said. All seven people on board were killed.

It was looking for the MiG-21 LanceR, which had lost contact and vanished from the radar shortly after the fighter jet – which was part of a formation of two MiG-21 LanceR planes executing air patrol missions – lost contact and disappeared from the radar.

The fighter plane was also discovered later Wednesday, the defense ministry said. It had crashed in Cogealac, an empty territory near the Black Sea. According to the report, the 31-year-old pilot perished.

'Apocalyptic night'

"It is early to speculate on potential causes. Certainly, there were adverse weather circumstances, but we cannot comment at the moment," General Constantin Spanu, the military's spokesman, told local television on Wednesday.

According to the ministry, the helicopter pilot reported unfavorable weather conditions and returned to base.

While the cause of the crash is being investigated, all IAR 330 Puma and MiG LanceR aircraft will be grounded.

On Thursday, all Romanian military units will hold military and religious mourning rituals for the victims.

President Klaus Iohannis expressed his condolences to the lost families of the crash victims in a statement issued Wednesday evening, describing the incident as "a tragic night for Romanian aviation."

In July 2010, 12 persons were killed, and two were injured when an AN-2 aircraft crashed shortly after takeoff on a parachute training flight assignment.

This prompted Romania's army to abandon the aircraft type, which was no longer deemed safe.

Later that month, an Israeli helicopter crashed in central Romania, killing six Israeli soldiers and a Romanian.

Occasionally, the MiG-21 LanceR will crash.

A Romanian Air Force pilot was killed in 2018 when his MiG-21 LanceR crashed during an air display in the southeast.

Although the Romanian Air Force is updating its aircraft, it continues to rely on Soviet-era MiGs for air policing duties.

The eastern flank of NATO

Romania, a former communist country that is now a member of NATO and the European Union, has received tens of thousands of refugees since Russia invaded neighboring Ukraine last week.

Romania has regularly asked troops for NATO's eastern flank in recent months of rising regional tensions. It has retaliated through its allies.

The US recently deployed a squadron of Stryker armored vehicles and approximately 1,000 troops to a Romanian base near the Black Sea, bringing 900 personnel stationed in the country.

And, during the last month, Germany's air force has added six Eurofighter Typhoon aircraft to the four comparable fighters Italy dispatched before the crisis.

This week, France sent around 500 soldiers to the eastern European country.