Ukraine has pulled back troops near several villages in the northeastern Kharkiv region, where Russian forces have been advancing and pounding settlements in a new offensive along the border, Kyiv said.
The military gave details of the pull back as US Secretary of State Antony Blinken was on an unannounced visit to Kyiv where President Volodymyr Zelensky urged him to speed up US supplies of weapons.
Moscow launched a surprise major ground assault on the Kharkiv region last week as it seeks to advance across the battlefield with Kyiv struggling for arms and manpower.
"In some areas, around Lukyantsi and Vovchansk, in response to enemy fire and assaults from ground troops, and to save the lives of our servicemen and avoid losses, our units manoeuvered and moved to more advantageous positions," the Ukrainian military said late Tuesday.
Throughout the two-year war, both sides have typically used the language of moving to more "advantageous positions" to signify retreats.
The two villages -- around 30 kilometres (18 miles) apart -- are close to the border with Russia and have been targeted in the fresh offensive.
Ukraine's General Staff said the situation "remains difficult" but insisted that its forces were "not allowing the Russian occupiers to gain a foothold".
Kyiv has rushed reinforcements to the area to prevent Russia from punching through.
Some military analysts say Moscow may be trying to force Ukraine to divert troops from other areas of the front line, such as around the strategic town of Chasiv Yar in the Donetsk region, where Russia has also been advancing.
"Donetsk and Kharkiv regions are where it is most difficult now," Zelensky said in an address on Tuesday evening.
Kyiv on Wednesday cancelled some emergency power blackouts that it had introduced to deal with a drop in temperatures that strained its battered energy system.
State power operator Ukrenergo had announced a series of overnight and early morning power cuts to deal with "the cold weather amid the consequences of Russian shelling" that has destroyed swathes of Ukraine's generating facilities.
"Emergency shutdowns in Kyiv, the Kyiv region, the Odesa region, the Donetsk region and the Dnipropetrovsk region were lifted," DTEK, the country's largest private energy operator said.
Blinken's visit came just weeks after the US Congress finally approved a $61-billion financial aid package for Ukraine following months of political wrangling, unlocking much-needed arms for the country's outgunned troops.
His visit began as the Russian defence ministry announced that its troops had captured two more villages in the Kharkiv region. During a meeting with Blinken, Zelensky asked for two more Patriot air defence systems to defend the border territory.
Ukrainian officials have said that more than 30,000 Russian forces have been deployed to the northeastern region but that the regional hub, the country's second-largest city of Kharkiv, was not threatened by the offensive.
