“The risk is serious, real. It should not be underestimated,” Russian Foreign Minister Sergei Lavrov said in a Russian state-television interview broadcast Monday night. “NATO is, in essence, going to war with Russia through a proxy and arming that proxy.”
Ukrainian Foreign Minister Dmytro Kuleba said Mr. Lavrov’s comments were aimed at scaring countries off supporting Ukraine. “This only means Moscow senses defeat in Ukraine,” he wrote on Twitter. “Therefore, the world must double down on supporting Ukraine so that we prevail and safeguard European and global security.”
Russia’s attempt to oust Ukraine’s elected government through a rapid military invasion at the end of February failed, and Moscow is now focusing on trying to seize territory in Ukraine’s east with the help of mass artillery and aerial bombardments.
The West is bolstering Ukraine with fresh supplies of weapons and ammunition in a bid to thwart Russia.
On Tuesday, Germany said it would refurbish and send to Ukraine decommissioned antiaircraft cannon tanks known as Flakpanzer Gepard, or Cheetah, ending its longstanding reluctance to give tanks to the country. Germany will provide about 50 of the German-made self-propelled guns, marking one of the first major deliveries of non-Soviet weapons systems by a Western country to Ukraine, two government officials said.
German Chancellor Olaf Scholz last week said his government was treading carefully to avoid a nuclear war.
The U.K. signaled a more aggressive stance toward Russia on Tuesday when a junior U.K. defense minister, James Heappey, said it was “completely legitimate” for Ukraine to use Western weapons to hit logistics and supply lines in Russia.
For months, the U.K. has provided weapons on the proviso that they are used to defend Ukraine from Russian attack rather than offensively.
“Things that the international community are now providing to Ukraine have the range to be used over the borders,” Mr. Heappey, who is U.K. minister for the Armed Forces, told Times Radio on Tuesday. “That is not necessarily a problem.”
Defense Secretary Lloyd Austin, meeting with defense ministers on Tuesday, said Ukraine has received more than $5 billion of equipment to defend against Russian forces, including two U.S. packages of military aid worth $800 million each.
A day earlier, Mr. Austin said that the U.S. aims to see Russia’s military capabilities degraded and Ukraine’s strengthened to prevent Moscow from attempting to conquer territory by force in the future.
“We want to see Russia weakened to the degree that it can’t do the kinds of things that it has done in invading Ukraine,” Mr. Austin said after he and Secretary of State Antony Blinken became the highest-level U.S. officials to visit the Ukrainian capital of Kyiv since Russia invaded Ukraine on Feb. 24.
Mr. Austin on Tuesday began meeting with other defense ministers, including Ukraine’s Oleksii Reznikov, and Secretary-General Jens Stoltenberg of the North Atlantic Treaty Organization at Ramstein Air Force Base in Germany. The topics on the agenda include updating the representatives of more than 40 countries about the latest intelligence from the battlefield in Ukraine, security assistance to Kyiv and strengthening NATO’s defense-industrial base in the long term to support Ukraine’s defense, a defense official said.
The defense ministers were expected to address Ukraine’s need for what NATO considers to be nonstandard ammunition and weapons systems, as well as discussions about whether the former Soviet republic could shift toward standard NATO equipment, the official said. For example, howitzers designed to fire 152-mm rounds can’t accommodate the 155-mm caliber.
The focus on heavy artillery and armored vehicles comes as Russia removes some of its forces from around cities in northern Ukraine and focuses instead on the eastern Donbas region, in a high-stakes conflict on wide-open terrain.
United Nations Secretary-General António Guterres was expected to meet with Mr. Lavrov and Russian President Vladimir Putin in Moscow on Tuesday, and with Ukrainian President Volodymyr Zelensky and Mr. Kuleba on Thursday to discuss ways to end the conflict.
Since Russian President Vladimir Putin ordered the invasion, he has repeatedly raised the specter of nuclear war, invoking his country’s atomic arsenal in an effort to deter the U.S. and the NATO from getting involved in the conflict.
But as Mr. Putin’s army has faced fierce resistance from Ukrainian forces strengthened by large infusions of Western weaponry, concerns have grown in Washington and allied capitals that Russia could consider using a so-called tactical nuclear weapon to gain the upper hand on the battlefield.
Earlier this month, Russia further warned that it could station nuclear forces in and around Kaliningrad—a Russian exclave wedged between Lithuania and Poland—and bolster its military presence there if Finland and Sweden join the NATO alliance.
Finland and Sweden are considering joining NATO and will make a decision in the coming weeks. Both countries have a long tradition of military neutrality, but the Russian invasion has tilted public opinion and the political consensus in both countries toward seeking membership in the U.S.-led alliance.
Mr. Lavrov said there has been no progress in peace negotiations with Kyiv, but that the conflict would end in a treaty that would depend on the situation on the ground. A senior U.S. official said Monday the U.S. aimed to ensure that Ukraine “has the strongest possible hand” in any such peace negotiations.
Bojan Pancevski and Max Colchester contributed to this article.