Russia and the United States are set to hold talks in Turkey on Thursday on normalising the work of their diplomatic missions after the war in Ukraine triggered the biggest confrontation between Moscow and the West since the depths of the Cold War.

A second round of talks between Russia and the U.S. was "constructive," the U.S. State Department said after delegations from both sides concluded discussions in Istanbul lasting nearly six hours.

The Russian delegation will be led by the newly appointed ambassador to the US, Alexander Darchiev, and the US team by Deputy Assistant Secretary of State Sonata Coulter, the Russian Foreign Ministry said.

The United States and Russia both said on Thursday that they had made progress toward normalising the work of their diplomatic missions, with the United States saying it was still concerned about a Russian policy prohibiting the employment of local staff.

U.S. citizen jailed for donating to a charity providing aid to Ukraine, her lawyer said on Thursday, in what the Wall Street Journal described as a swap for a Russian-German national jailed in the United States.

A Russian-American woman who was imprisoned for treason by Russia has been freed, Secretary of State Marco Rubio said Thursday. Former ballerina Ksenia Karelina was born in Russia but had built a new life as an aesthetician at a Los Angeles spa after immigrating to the United States over a decade ago.