Russia's Main Anti-NATO Unit Retreats During Ukraine Counteroffensive: U.K.

A top Russian unit has retreated from the Kharkiv region amid Ukraine's successful counteroffensive, according to a report from the British Ministry of Defense.

In its daily intelligence update on the Russian President Vladimir Putin's war in Ukraine, the U.K.'s defense ministry said Russia's capability to counter the North Atlantic Treaty Organization (NATO) has likely been severely weakened as a result of the casualties it has sustained in Kyiv's push to retake the Kharkiv Oblast (province).

"Elements of the Russian forces withdrawn from Kharkiv Oblast over the last week were from the 1st Guards Tank Army (1 GTA), which are subordinate to the Western Military District (WEMD)," it said in a tweet Tuesday.

The British defense ministry noted that the1 GTA suffered heavy casualties in the initial phase of Putin's invasion, which began on February 24, and had not been fully reconstituted prior to the Ukrainian counteroffensive in Kharkiv.

"1 GTA had been one of the most prestigious of Russia's armies, allocated for the defence of Moscow, and intended to lead counter-attacks in the case of a war with NATO," the ministry's update said.

It added: "With 1 GTA and other WEMD formations severely degraded, Russia's conventional force designed to counter NATO is severely weakened. It will likely take years for Russia to rebuild this capability."

Ukrainian President Volodymyr Zelensky said during a video address on Monday night that Ukraine has recaptured some 6,000 square kilometers (2,400 square miles) of territory since the beginning of September, when a surprise Kharkiv counteroffensive began.

On Sunday the commander of Ukraine's military, General Valeriy Zaluzhnyi, said his troops had regained 3,000 square kilometers (1,158 square miles) of territory from the Russians.

Russia's Defense Ministry said its troops retreated from the Izyum and Balakliya areas over the weekend to "regroup." Izyum is a major base for Russian forces in the Kharkiv region.

Ukraine has also claimed to have destroyed key Russian units during its counteroffensive.

On Monday, the General Staff of the Armed Forces of Ukraine said on its Facebook page that the Ukrainian military had destroyed almost 85 percent of Russia's 810 marine infantry brigade, which is based in the city of Sevastopol in the Russian-occupied Crimean Peninsula

"After the successful actions carried out by the Defense Forces in the Kherson direction, the enemy suffered significant losses in manpower," it said.

Ukraine said Russian service personnel have extremely low morale and "massively refuse to return to the combat zone."

Newsweek was unable to verify the claims and contacted Russia's Foreign Ministry for comment.