Russia has redoubled its efforts to take Bakhmut by increasing its troop numbers deployed to the Donetsk town, according to British defense officials.

Following "tactical gains" by Ukraine on the flanks of Bakhmut this month, Russia has "likely redeployed" several battalions to reinforce the sector, the U.K. Ministry of Defense said on Saturday.

"With Russia likely maintaining relatively few uncommitted combat units in Ukraine, the redeployment represents a notable commitment by the Russian command," the defense officials said.This was because Moscow probably saw capturing Bakhmut "as the key immediate war aim which would allow them to claim some degree of success in the conflict," added the update, which tends to emphasize Russian losses and Ukrainian gains. Newsweek has contacted the Russian Defense Ministry for comment. A separate assessment by the Institute of the Study of War (ISW) said that Ukrainian counterattacks had probably stopped the chances of Russian forces encircling the area, despite an increased number of troops there. 

These counterattacks are likely to have forced Moscow to "allocate scarce military resources to defend against a limited and localized offensive effort," the think tank said on Friday.

Earlier that day, Serhii Cherevatyi, a spokesperson for Ukrainne's Eastern Operational Command, said Kyiv's forces were gaining the upper hand near the town fought over for months, advancing up to 500 meters in one flank and 1,000 meters on the other.

Wagner Group mercenaries led by Yevgeny Prigozhin have been spearheading Moscow's efforts to take Bakhmut. In a tweet on Saturday, military expert Rob Lee cited a satellite map as showing that Wagner forces had taken the western part of the town and that Ukrainian forces held its southwest corner.

Prigozhin has threatened to withdraw his forces and is reportedly in contact with Ukrainian intelligence, according to revelations from Pentagon leaks that he has denied.

However, some Russian military bloggers have claimed that the Ukrainian forces are unable to sustain prolonged localized counterattacks around Bakhmut, although the ISW said that Russian forces on the town's flanks "likely remain weak."

Separately, the United States will train Ukrainian pilots on F-16 jet fighters and help allies supply the planes to Kyiv, U.S. national security advisor Jake Sullivan announced in a press briefing.

Ukraine has long been calling for the jets to counter Russian aggression and training on them will take place in the coming months, however, Kyiv's allies have not yet decided which of them will provide the aircraft, or how many.