Vladimir Putin has lost his 56th colonel to the war in Ukraine with a strike by a newly-supplied US medium range HIMARS missile.
Paratrooper commander Colonel Andrei Vasilyev, 49, was killed in an attack on Friday night.
His death is one of the first from the new 43-mile-range weapons sent to Ukraine by President Joe Biden.
He was in an advanced command post of the Russian army’s airborne assault troops, but the location was not specified.
Vasilyev was commander of the 137th Guards Airborne Regiment of the 106th Guards Airborne Division, based in Ryazan.
Married with a daughter, he had been awarded the Russian Order of Courage on other honours.
Footage shows the launch of the first HIMARS missiles in Ukraine late last week.
It is unclear whether this is the strike that killed Vasilyev in the Friday attack.
A separate HIMARS attack on Izyum, Kharkiv region hit a Russian base, killing or wounding 40-plus, according to Ukraine.
Russian military holed up in a school in Izyum were hit by the new missile which which has a range of around 43 miles.
The blast wreaked havoc at the old school site which was said to be used as a Russian command post.
Smoke was seen billowing from small fires surrounding the school where windows were smashed and debris covered the floor.
It was the precision-guided weapon's first hit on Russian military command position.
The 55th colonel to die was Lt-Col Sergey Gundorov, 51, whose helicopter was seen crashing in an inferno near Volnovakha in the Donbas, after being hit with a portable surface-to-air missile.
His stricken Mi-35 touched the ground before cartwheeling over a narrow strip of woodland and crashing in a fireball in a field.
Putin has also lost at least 11 generals.
Overall Russian losses are believed to be in excess of 30,000, with some estimates of nearer to 50,000.
Monday marked 124 days since Putin's troops invaded Ukraine on February 24.
Ukraine's president Volodymyr Zelensky has called for a more modern air defence system for his country after a string of deadly attacks on the capital of Kyiv.
Other regions that have been severely hit include Mykolaiv, Chernihiv and Lviv.
Elsewhere in the Russian-occupied city of Mariupol, more than 100 bodies were found in a house, according to the mayor’s adviser Piotr Andryushchenko.
On Sunday, Moscow's forces entered the city of Lysychansk from five directions and were isolating Ukrainian troops, according to a separatist official.
