Russia may have lost about a third of its military forces in Ukraine since the start of the war on February 24, the UK’s Ministry of Defense said in a bulletin released today. The Russian offensive in the separatist Donbass region, which includes Donetsk and Lugansk, “lost momentum and was significantly delayed,” British intelligence said.

“Despite initial small-scale advances, Russia failed to make significant territorial gains in the past month and has maintained consistently high attrition levels,” the Defense Department said on Twitter.

“Russia has probably lost a third of the ground combat power it had committed in February,” the publication said.

Still, according to British officials, it is “unlikely” that Russia will greatly accelerate its pace of progress over the next 30 days.

Since the invasion of Russia in February, Ukrainian troops have forced Russian forces to abandon an advance in the capital, Kiev, while also driving them away from Kharkiv, the country’s second largest city.

A Ukrainian counteroffensive is also underway near the Russian-controlled city of Izium, although the Ukrainian military reported today that Russian forces are advancing elsewhere in the Donbass region.

“The Russians are gathering equipment and manpower close to Severodonetsk and preparing to attack it,” Serhiy Hayday, head of Lugansk’s regional military administration, said this morning.

Severodonetsk is one of several industrial cities that have been bombarded for weeks as the Russian army in the east tries to tear down the Ukrainian defenses. Hayday said the city’s chemical factory and skyscrapers were hit.

Counter-offensive in Kharkov

Ukraine said that despite new attacks, it also launched a counterattack in Kharkov and was successful in retaking areas previously occupied by Russian troops. However, Ukrainian officials gave little detail on the situation in the region.

According to official communiqués, Ukraine’s aim here is to cut off the Russian supply lines of its forces trying to advance into the Donetsk region.

The head of Kharkiv’s regional military administration, Oleh Syniehubov, said that Ukrainian troops are constantly strengthening their positions and pushing military personnel from the borders of the city to the borders of Russia. “North and northeast directions are the warmest; there are active hosts there,” Syniehubov added.