KYIV, Ukraine (AP) – Russia unleashed a string of attacks Monday against rail and fuel installations deep inside Ukraine, far from the front lines of Moscow’s new eastern offensive, as Russia’s top diplomat warned against provoking World War III and said the threat of a nuclear conflict “should not be underestimated.”

The U.S., meanwhile, moved to rush more weaponry to Ukraine and said the assistance from the Western allies is making a difference in the two-month-old war.

“Russia is failing. Ukraine is succeeding,” U.S. Secretary of State Antony Blinken declared, a day after he and the U.S. secretary of defense made a visit to Kyiv to meet with President Volodymyr Zelenskyy.

Mr. Blinken said Washington approved a $165 million sale of ammunition—non-U.S. ammo, mainly if not entirely for Ukraine’s Soviet-era weapons—and will also provide more than $300 million in financing to buy more supplies.

U.S. Defense Secretary Lloyd Austin took his comments further, saying that while the U.S. wants to see Ukraine remain a sovereign, democratic country, it also wants “to see Russia weakened to the point where it can’t do things like invade Ukraine.”

Mr. Austin’s comments about weakening Russia appeared to represent a shift in broader U.S. strategic goals. Previously, the U.S. position had been that the goal of American military aid was to help Ukraine win and to defend Ukraine’s NATO neighbors against Russian threats.

Russian Foreign Minister Sergei Lavrov said weapons supplied by Western countries “will be a legitimate target,” adding that Russian forces had already targeted weapons warehouses in western Ukraine.

“Everyone is reciting incantations that in no case can we allow World War III,” Mr. Lavrov said in a wide-ranging interview on Russian television. He accused Ukrainian leaders of provoking Russia by asking NATO to become involved in the conflict.

By providing weapons, NATO forces are “pouring oil on the fire,” he said, according to a transcript on the Russian Foreign Ministry’s website.

Regarding the possibility of a nuclear confrontation, Mr. Lavrov said: “I would not want to see these risks artificially inflated now, when the risks are rather significant.”

“The danger is serious,” he said. “It is real. It should not be underestimated.”

When Russia invaded Ukraine on February 24, its apparent goal was the lightning capture of Kyiv, the capital. But the Ukrainians, with the help of Western weapons, thwarted the push and forced President Vladimir Putin’s troops to retreat.

Moscow now says its goal is to take the Donbas, the mostly Russian-speaking industrial region in eastern Ukraine. While both sides say the campaign in the east is underway, Russia has yet to mount an all-out ground offensive and has not achieved any major breakthroughs.