Melania Trump says she has an "open" line of communication with Vladimir Putin on the fate of children abducted by Russia during the Ukraine war.
Eight children had been reunited with their families in the last 24 hours, she added.
Speaking at the White House on Friday, local time, the US first lady said she expected more to be reunited soon after further talks between her team and the Russian president's.
"Much has unfolded since President Putin received my letter last August," she said, referring to a note that was passed on by President Donald Trump when he met Mr Putin in Alaska.
"He responded in writing signalling a willingness to engage with me directly and outlining details regarding the Ukrainian children residing in Russia," she told reporters.
"Since then, President Putin and I have had an open channel of communication regarding the welfare of these children."
The Slovenian-born former model said that both sides had also had "several back channel meetings and calls, all in good faith".
"My representative has been working directly with President Putin's team to ensure the safe reunification of children with their families between Russia and Ukraine," she said.
"In fact, eight children have been rejoined with their families during the past 24 hours," she said, adding that one of them had been displaced by fighting and was returning from Ukraine to Russia.
Power outage in Kyiv
Meanwhile in Ukraine, where Russia continues to wage its war, large parts of Kyiv were plunged into darkness on Friday.
Russian drones and missiles struck Ukrainian energy facilities in the early hours of the morning, local time, cutting power and water to homes and halting a key metro link across the Dnipro River.
In the latest mass attack targeting the energy system as winter approaches, electricity was interrupted in nine regions, and more than a million households and businesses were temporarily without power across the country.
Ukraine's prime minister called it one of the heaviest such strikes to date.
In south-eastern Ukraine, a seven-year-old was killed when his home was hit and at least 20 people were injured.
In Kyiv, an apartment block in the city centre was damaged by a projectile, while on the left bank of the Dnipro that divides the capital, crowds waited at bus stops with the metro out of action and people filled water bottles at distribution points.
According to Ukraine's energy ministry, over 800,000 customers lost power in Kyiv because of the attack, with 380,000 still disconnected on Friday afternoon.
Ukrainians are bracing for a tough winter, as the full-scale war nears its fourth anniversary.
Russia has intensified attacks on the energy system in recent weeks, striking power plants and gas production facilities, and local authorities are struggling with the scale of repairs required.
"It is precisely the civilian and energy infrastructure that is the main target of Russia's strikes ahead of the heating season," President Volodymyr Zelenskyy said on X.
Calling for more support from Kyiv's allies, he said: "What's needed is not window dressing but decisive action – from the United States, Europe, and the G7 – in delivering air defence systems and enforcing sanctions."
Mr Trump has repeatedly expressed frustration in recent weeks at the continuation of the war in Ukraine, which he had promised, as candidate for the presidency, that he would end within a day.
ABC/wires