Two top Russian pilots were killed by the Ukrainians.
The father of one of the pilots told the Russians.
The US has sentUkraine 12 units so far.
The US supplied the long-range rocket system that killed the two Russian pilots.
The MailOnline reported that Lieutenant Colonel Maksim Potyomin was killed when his motorcade was hit by rocket fire.
Colonel Anatoly Stasyukevich is thought to have died in the same attack.
The father of Maksim Potyomin told a Russian outlet that he believed his son's death was caused by a strike.
Potyomin said that his son's injuries were incompatible with life after he was hit by a missile.
The pilot was buried with full military honors after his funeral on Sunday.
The 1st Guards Baranovichi Red Banner mixed aviation division had two pilots. According to reports, it was the first unit to receive the fifth- generation fighters.
The HIMARS, which arrived in Ukraine last month, has begun to play a crucial role in the fight against Russia.
According to Gen. Mark Milley, the US has givenUkraine 12 units so far.
A military expert told Insider's Sinéad Baker that senior commanders were forced into its range due to poor Russian Logistics.
They can hit targets as far away as 50 miles away, and are more advanced than the Ukrainians.
The weapons were used to kill a Russian general and destroy 50 depots.
Putin threatened to escalate his bombing campaign after the US sent weapons to Ukraine.
Dozens of senior Russian officers have been killed in Ukranian.
Business Insider has an article on it.