KYIV, April 25 - 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 2-month-old war, The Associated Press reported.

“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 bold visit to Kyiv to meet with President Volodymyr Zelenskyy.

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.”

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.

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

When Russia invaded Ukraine on Feb. 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.

On Monday, Russia focused its firepower elsewhere, with missiles and warplanes striking far behind the front lines in an effort to thwart Ukrainian efforts to marshal supplies for the fight.

Five railroad stations in central and western Ukraine were hit, and one worker was killed, said Oleksandr Kamyshin, head of Ukraine’s state railway. The bombardment included a missile attack near Lviv, the western city close to the Polish border that has been swelled by Ukrainians fleeing the fighting elsewhere around the country.

Ukrainian authorities said at least five people were killed by Russian strikes in the central Vynnytsia region.

Russia also destroyed an oil refinery in Kremenchuk, in central Ukraine, along with fuel depots there, Russian Defense Ministry spokesman Maj. Gen. Igor Konashenkov said. In all, Russian warplanes destroyed 56 Ukrainian targets overnight, he said.

Philip Breedlove, a retired U.S. general who was NATO’s top commander from 2013 to 2016, said the latest strikes against fuel depots are part of a strategy to deplete key Ukrainian war resources. The strikes against rail targets, on the other hand, are a newer tactic, he said. (ap/ez)