The British government announced Thursday it was giving long-range cruise missiles to Ukraine to help drive out Russia’s occupying forces, just as Kyiv delayed a possible counteroffensive more than 14 months after the Kremlin’s full-scale invasion as it awaits the delivery of more Western weapons.

U.K. Defense Secretary Ben Wallace told lawmakers in the House of Commons that Britain is donating Storm Shadow missiles, a conventionally-armed deep-strike weapon with a range of more than 250 kilometers (150 miles).

That means it can hit targets deep behind the front line, including in Russia-occupied Crimea. U.K. media reported that Ukraine has pledged not to use the missiles to attack Russia itself.

Wallace said the missiles “are now going into or are in the country itself.”

Ben Hodges, a former U.S. Army Europe Commanding General, tweeted: ““Well done UK!”

He added: “This will give Ukraine capability to make Crimea untenable for Russian forces” and would force a Russian rethink of where to position its Black Sea fleet.

The British move gives another boost to the Ukrainian military after it received other advanced Western weapons including tanks and long-range precision artillery.

The announcement came shortly after Ukrainian President Volodymyr Zelenskyy said his country’s military needs more time to prepare an anticipated counteroffensive aimed at pushing back Russian occupying forces and opening a new chapter in the war more than 14 months after the Kremlin’s full-scale invasion.

Zelenskyy said in an interview broadcast Thursday by the BBC that it would be “unacceptable” to launch the assault now because too many lives would be lost.

“With (what we have) we can go forward and be successful,” Zelenskyy said in the interview, according to the BBC.

“But we’d lose a lot of people. I think that’s unacceptable,” he was quoted as saying. The interview was reportedly carried out in Kyiv with public service broadcasters who are members of Eurovision News, including the BBC.

“So we need to wait. We still need a bit more time,” Zelenskyy was quoted as saying.

A Ukrainian fightback against Russia's invasion has been expected for weeks. Ukraine is receiving Western training as well as advanced weapons for its troops as it gears up for an expected assault.

While a counterpunch is possible as the weather in Ukraine improves, there has been no word on when it might happen. Zelenskyy’s remarks could be a red herring to keep the Russians guessing, and ammunition supply difficulties faced by both sides have added more uncertainty.

A claim by the Ukrainian military on Wednesday that it had advanced up to two kilometers (1.2 miles) around the hotly contested eastern city of Bakhmut brought speculation that the counteroffensive was already underway.

But Serhii Cherevatyi, spokesman for Ukraine’s Operational Command East, told The Associated Press that the attack was not the “grand counteroffensive, but it’s a harbinger showing that there will be more such attacks in the future.”

The Kremlin's forces are deeply entrenched in eastern areas of Ukraine with layered defensive lines reportedly up to 20 kilometers (12 miles) deep. Kyiv's counteroffensive would likely face minefields, anti-tank ditches and other obstacles.

Russia is “acting slow” in Ukraine because it wants to preserve infrastructure and save lives there, Kremlin spokesman Dmitry Peskov claimed in an interview with the Bosnian Serb channel ATV broadcast Wednesday night.

Moscow has repeatedly explained its lack of advances on the battlefield as an effort to protect civilians, but those claims have been proven false.

Zelenskyy said Russian President Vladimir Putin is counting on reducing the war to a so-called frozen conflict, with neither side able to dislodge the other, according to the BBC. He ruled out surrendering territory to Russia in return for a peace deal.

Military analysts have warned that Putin is hoping that the West’s costly support for Kyiv will begin to fray.

Ukraine’s Western allies have sent the country 65 billion euros ($70 billion) in military aid to help thwart the Kremlin’s ambitions, and with no peace negotiations on the horizon the alliance is gearing up to send more.