MOSCOW/KYIV — Russia and Ukraine continued aerial attacks on each other, officials said on Sunday, as the fate of a proposed ceasefire to the three-year-old conflict remained uncertain.

Russian President Vladimir Putin said on Thursday he supported in principle Washington's proposal for a 30-day cease-fire with Ukraine but that his forces would fight on until several crucial conditions were worked out.

Both sides have since traded heavy aerial strikes, and Russia moved closer on the battlefield to ejecting Ukrainian forces from their months-old foothold in the western Russian region of Kursk.

The Russian defense ministry said on Sunday that its air defense units destroyed a total of 31 Ukrainian drones over Russian territory.

Of those, 16 were downed over the southwestern region of Voronezh, nine over the territory of the Belgorod region and the rest over the Rostov and Kursk regions, the ministry said on the Telegram messaging app.

In a Ukrainian drone attack on the Russian border region of Belgorod, three people were injured, including a 7-year-old, regional Governor Vyacheslav Gladkov said earlier on Telegram.

Two of the people were injured after a drone hit their house, sparking a fire in the Gubkinsky district of the region, while the other person was injured in a drone attack on the village of Dolgoye, Gladkov said.

Alexander Gusev, governor of Voronezh, said on Telegram that there were no immediate reports of injuries or damage.

The acting governor of the southern Russian region of Rostov said there were no immediate reports of injuries or damage reported there either.

In Ukraine, authorities reported several Russian drone strikes, including on the northern region of Chernihiv, where firefighters were battling a blaze at a high-rise building that was sparked by a Russian drone attack, Ukraine's state of emergency service said.

Ukrainian media reported a series of explosions in the region surrounding the capital Kyiv, after Ukraine's air force issued warnings of a threat of drone attacks on Kyiv and a number of other central Ukrainian regions.

Diplomatic efforts

While there were no signs of easing on the battlefield, diplomatic efforts were underway to resolve the conflict.

US Secretary of State Marco Rubio and Russia's Foreign Minister Sergey Lavrov, in a call on Saturday, "discussed next steps", US State Department spokeswoman Tammy Bruce said.

The statement gave no details on when the next round of US-Russia talks hosted by Saudi Arabia would begin.

But Rubio and Lavrov also "agreed to continue working toward restoring communication between the United States and Russia", Bruce added.

Since returning to the White House in January, US President Donald Trump has stressed his desire to end the conflict. Trump on Saturday appointed Keith Kellogg as special envoy to Ukraine.

A former national security adviser during Trump's first term, Kellogg had previously been described as a special envoy for both Ukraine and Russia.

But he was excluded from recent talks in Saudi Arabia on ending the conflict, with NBC News in the United States citing a senior Russian official who said Putin considered him too pro-Ukraine.

The diplomats' call came after a virtual summit hosted by London earlier on Saturday.

At those talks, British Prime Minister Keir Starmer told some 26 fellow leaders that they should focus on how to strengthen Ukraine, protect any cease-fire and keep up the pressure on Moscow.

Speaking to reporters in Kyiv on Saturday, after virtual talks between Western allies hosted by Starmer, President Volodymyr Zelensky voiced Ukraine's support for the 30-day full cease-fire proposal to discuss a longer-term peace plan, but said Russia would attempt to derail talks with conditions and "buts".

Starmer said the "ball was in Russia's court" and that Putin would "sooner or later" have to "come to the table".

Military leaders from about 30 countries met in Paris on March 11 to discuss plans for a peacekeeping force in Ukraine, and will meet again Thursday in Britain.

Agencies via Xinhua