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

The U.S., meanwhile, moved Monday to rush more weaponry to Ukraine and said the assistance from Western allies is making a difference in the 2-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 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 remarks 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.