Russian forces on Thursday launched massive missile strikes on Ukraine's Kyiv and Chernihiv regions, areas that haven't been targeted in weeks, while Ukrainian officials announced an operation to liberate an occupied region in the country's south.

Kyiv regional governor Oleksiy Kuleba said on Telegram that a settlement in the Vyshgorod district of the region was targeted early on Thursday morning; an “infrastructure object” was hit. It wasn't immediately clear if there were any casualties.

Chernihiv governor Vyacheslav Chaus at the same time reported that multiple missiles were fired from the territory of Belarus at the Honcharivska community.

Russian troops withdrew from the Kyiv and Chernihiv regions months ago, failing to capture either. The renewed strikes on the areas come a day after the leader of pro-Kremlin separatists in the east, Denis Pushilin, publicly called on the Russian forces to “liberate Russian cities founded by the Russian people — Kyiv, Chernihiv, Poltava, Odesa, Dnipropetrovsk, Kharkiv, Zaporizhzhia, Lutsk.”

Kharkiv, Ukraine's second largest city, also came under a barrage of shelling overnight, its mayor Ihor Terekhov said. The southern city of Mykolaiv was fired at as well, with one person sustaining injuries.

Meanwhile, the Ukrainian military continued to counterattack in the occupied southern region of Kherson, striking a key bridge over the Dnieper River on Wednesday.

Ukrainian media on Thursday quoted Ukraine's presidential adviser, Oleksiy Arestovich, as saying that the operation to liberate Kherson “has already begun.” Arestovich said Kyiv's forces were planning to isolate Russian troops there and leave them with three options — to "retreat, if possible, surrender or be destroyed."

Oleksiy Danilov, the secretary of Ukraine’s National Security and Defense Council, in televised remarks on Wednesday said he was “cautious” in assessing the timeline of the possible counteroffensive. “I would really like it to be much faster,” he said, adding that “the enemy is now concentrating the maximum number (of forces) precisely in the Kherson direction.”

“A very large-scale movement of their troops has begun, they are gathering additional forces,” Danilov warned.

The British military estimated Thursday that Ukraine’s counteroffensive in Kherson is “gathering momentum”.

“Their forces have highly likely established a bridgehead south of the Ingulets River, which forms the northern boundary of Russian-occupied Kherson," the British Defense Ministry said on Thursday.

It added that Ukraine has used its new long-range artillery to damage at least three of the bridges across the Dnieper River, "which Russia relies upon to supply the areas under its control." The 1,000-meter-long Antonivsky bridge, which Ukrainian forces struck on Wednesday, is likely to be “unusable,” the British Defense Ministry concluded.