US President Joe Biden has said Russia's decision to withdraw from the Ukrainian city of Kherson shows its military has "some real problems".
Mr Biden said he had been expecting the move for "some time" and that it would allow both sides to "recalibrate their positions" over the winter.
Kherson is the only major Ukrainian city to fall to Russian forces. Ukraine is treating the news of the withdrawal with scepticism, saying it would move "very carefully".
Gen Sergei Surovikin, who was made Russia's commander in Ukraine just weeks ago, announced the withdrawal on Wednesday accompanied by the military top brass on Russian state TV.
He confirmed Russian troops would pull back entirely from the western bank of the River Dnipro. It is a significant blow to Russia's military ambitions as it faces a Ukrainian counter-offensive.
Mr Biden was speaking from the White House after midterm elections in which his Democratic Party looked likely to lose control of the House of Representatives to the opposition Republican Party.
The president's political rivals previously vowed to review US military and humanitarian aid to Ukraine
Mr Biden observed that it was "interesting" that Moscow had "waited until after the election" to announce the withdrawal.
But he said he hoped the "bipartisan approach of confronting Russia's aggression in Ukraine" would continue.