Germany announced plans on Wednesday to deliver heavy tanks to Ukraine, and the United States was poised to do so too, a breakthrough hailed as a decisive military boost by Kyiv and condemned by Moscow as a reckless provocation.
Kyiv has been calling for months for Western main battle tanks that would give its forces greater firepower, protection and mobility to break through Russian defensive lines and potentially swoop through territory occupied by the invaders.
"A few hundred tanks for our tank crews .... This is what is going to become a real punching fist of democracy," Andriy Yermak, the head of Ukrainian President Volodymyr Zelensky's administration, wrote on Telegram.
Germany will send an initial company of 14 Leopard 2 tanks from its own stocks and approve shipments by allies who field them, with the aim of supplying Ukraine with two battalions, typically comprising three-four companies each. Berlin would also provide training, ammunition and maintenance.
"This decision follows our well-known line of supporting Ukraine to the best of our ability. We are acting in a closely coordinated manner internationally," Chancellor Olaf Scholz said in a statement.
Two sources in the United States said Washington would also provide dozens of its Abrams M1 tanks.
Kremlin spokesman Dmitry Peskov said any US tanks sent to Ukraine would "burn like all the rest".
Twenty armies worldwide field Leopards, which Germany has made in their thousands. Poland and Finland have already pledged them once Berlin agrees, and several other countries are expected to follow swiftly. Britain has already offered a company of its comparable Challengers and France is considering sending its Leclercs.
Mark Hertling, a former commander of US ground forces in Europe, estimated Leopards could reach Ukraine's battlefields as soon as March. The turbine-powered US tanks, which need more logistical support, could be more than eight months away.
Moscow says supplies of modern offensive weaponry to Ukraine will prolong the war and postpone what it says will be its inevitable victory. Anatoly Antonov, Russia's ambassador in Washington, said deliveries of US battle tanks would be a "another blatant provocation".
"It is obvious that Washington is purposefully trying to inflict a strategic defeat on us," Antonov said on the embassy's Telegram messaging channel.
In the past week, Russia has ramped up its threats, with Dmitry Medvedev, an ally of President Vladimir Putin, saying openly that a nuclear power that faced defeat could use nuclear weapons.
Western officials who support sending the tanks have dismissed Moscow's threats as bluster, saying Russia is already waging war at full tilt and has been deterred from attacking NATO or using nuclear arms.
"The right decision by NATO Allies and friends to send main battle tanks to Ukraine. Alongside Challenger 2s, they will strengthen Ukraine’s defensive firepower," British Prime Minister Rishi Sunak wrote on Twitter.
Polish Prime Minister Mateusz Morawiecki tweeted a message of thanks to Scholz for a "big step towards stopping Russia".
The decision lifts one of the last taboos in Western support: providing weapons that have a mainly offensive rather than defensive purpose.
Last week, allies pledged billions of dollars' worth of new military aid but stopped short of sending the tanks, with some politicians in Germany wary of provoking Moscow.
The pledges of recent weeks already include hundreds of Western armoured fighting vehicles and troop carriers, seen as more effective in attacking when combined with tanks to burst through enemy lines.
DOZENS OF TANKS
In the 11 months since it invaded, Russia has killed thousands of civilians, forced millions from their homes and reduced entire cities to rubble.
It says its "special military operation" was necessary to stem a security threat arising from Ukraine's ties to the West, which it now portrays as seeking to destroy it. Kyiv and its allies say Ukraine never threatened Russia, and the invasion is a war of aggression to subdue its neighbour and seize land.
Ukraine defeated Russia's troops on the outskirts of Kyiv last year and later drove them out of swathes of occupied land.
But Moscow still occupies around a sixth of Ukraine, and has declared this territory part of Russia. Ukraine says it will not stop fighting until it recaptures all its territory.
The front line has been largely frozen in place for two months despite heavy losses on both sides, with both believed to be planning new offensives for the spring.
Zelensky said Russia was intensifying its push toward Bakhmut, an industrial town in eastern Ukraine where thousands of troops have been killed in trench battles that both sides refer to as a meat grinder.
The Russian-installed governor of Ukraine's Donetsk region said units of Russia's Wagner contract militia were now moving forward inside Bakhmut, with fighting on the outskirts and in neighbourhoods recently held by Ukraine.
Reuters could not verify the situation there.