A critical bridge shelled. A fighter jet shot out of the sky. Ammunition depots destroyed. A cluster of soldiers attacked.

Ukraine’s intensifying attacks on Russian forces in just the last 48 hours in Kherson Province are raising a question: Is the ground being laid for a broad counteroffensive?

The southern city of Kherson fell to Russian forces in early March, and Moscow is now trying to absorb the province. Kherson, a port and shipbuilding center, is also a staging ground for Russia’s military operations across southern Ukraine.

That means any attempt to recapture the city would have immense strategic and symbolic value for the government of President Volodymyr Zelensky. A counteroffensive also would signal a significant shift in the war, and the timing is critical. A Pentagon spokesman said on Tuesday that Russia planned to annex territories it has captured, including Kherson.

“Ukraine and its Western partners may have a narrowing window of opportunity to support a Ukrainian counteroffensive into occupied Ukrainian territory before the Kremlin annexes that territory,” said the spokesman, John Kirby.

Since April, Ukrainian forces have effectively been locked into a defensive posture as they gradually retreated from an onslaught of Russian artillery in the eastern Donbas region. The Russians have not seized new territory in weeks, and the Ukrainians say their defensive positions have stabilized.

But the purpose of the longer-range missile systems that Ukraine has been pleading for, and that Western countries have increasingly started to supply to its government, is not just to forestall Russia’s advance, but also to win back lost territory.

“We all strive to liberate Ukraine from the enemy,” the spokeswoman for Ukraine’s southern forces, Natalia Humeniuk, said on Tuesday. “We have a single goal.”

Ukraine used a HIMARS artillery weapon, newly supplied by the United States, to hit the Antonivsky bridge in Kherson on Tuesday, an adviser to country’s interior minister said. The bridge has been the main transit route for Russian supplies coming in from Crimea, which Moscow annexed in 2014. Eleven more missiles hit the bridge on Wednesday, according to the deputy head of the pro-Russia administration in Kherson.

The bridge is a “key vulnerability for Russian forces,” a British intelligence report said.

Ukraine’s armed forces also said on Wednesday that they had blown up a Russian radar system in Kherson using missiles fired from more than 60 miles away — a day after Ukraine’s air force command said it had shot down a Russian fighter jet above agricultural land in Kherson and struck warehouses that are crucial for resupplying Russia’s forces west of the Dnipro River.

Ukrainian forces also struck a cluster of Russian forces, an adviser to the head of the province’s military administration said on Tuesday, adding that casualties were still being assessed.

Those accounts could not be independently verified, although some of the attacks were captured on video.

Since May, Ukrainian forces have fought a series of skirmishes in northern Kherson, reclaiming villages, targeting rail lines and fighting for control of roads. It has been unclear whether the advances were primarily intended to divert Moscow’s forces from larger battles in Donbas or were the prelude to a bigger regional push.

If Ukraine does mount a broad counteroffensive, it will force both sides to confront difficult decisions, military analysts say. For Mr. Zelensky, it will test whether his forces are capable of doing more than holding their ground and whether his vow to reclaim ground lost to Russia since 2014 is feasible.

Russia’s military, on the other hand, would need to decide how deeply to commit to the defense of a territory, particularly if the bridge is destroyed and the resupply of its forces under attack becomes more difficult.