Buckingham Palace said Sophie met with Ukraine President Volodymyr Zelenskyy and First Lady Olena Zelenska, and delivered them a handwritten message of support from King Charles III.

The duchess also paid her respects at the site of a mass grave in Bucha, and visited a cathedral in Kyiv.

Buckingham Palace said the purpose of the duchess’ visit was “to demonstrate solidarity with the women, men and children impacted by the war and in a continuation of her work to champion survivors of conflict-related sexual violence.”

The timing and other details of the trip were not disclosed.

Before Duchess Sophie’s visit, the closest a British royal had come to the conflict was a visit by William, Prince of Wales, to a military base in Poland, where he thanked UK troops for their service.

The announcement from the palace comes on the heels of a declaration from NATO Secretary-General Jens Stoltenberg that the alliance’s delays in replenishing Ukraine’s weapons stockpile was handing Russia a battlefield advantage.

Outgunned, Ukraine’s troops have struggled to fend off Russian advances on the battlefield.

They were recently compelled to make a tactical retreat from three villages in the east, where the Kremlin’s forces have been making incremental gains, Ukraine’s army chief said Sunday. The Russian Defence Ministry claimed on Monday (Tuesday AEST) its forces had also taken the village of Semenivka.

“The lack of ammunition has allowed the Russians to push forward along the front line. Lack of air defence has made it possible for more Russian missiles to hit their targets, and the lack of deep strike capabilities has made it possible for the Russians to concentrate more forces,” Stoltenberg said.

Kyiv’s Western partners have repeatedly vowed to stand with Ukraine “for as long as it takes”.

But vital US military help was held up for six months by political differences in Washington, and Europe’s military hardware production has not kept up with demand. Ukraine’s own manufacturing of heavy weapons is only now starting to gain traction.

Now, Ukraine and its Western partners are racing to deploy critical new military aid that can help check the slow and costly but steady Russian advance across eastern areas, as well as thwart drone and missile attacks.

Zelenskyy said new Western supplies have started arriving, but slowly.

“This process must be speeded up,” he said at a news conference with Stoltenberg.