YIV, Ukraine (AP) — Western nations promised more and more advanced arms to bolster Ukraine's defense as its troops battled a grinding Russian offensive that was closing in on capturing a key city in the east.

Germany said Wednesday it will supply Ukraine with modern anti-aircraft missiles and radar systems, and the U.S. will unveil a new weapons package later in the day that will include high-tech, medium-range rocket systems.

The Kremlin spokesman told reporters Wednesday that the U.S. is “pouring fuel on the fire.”

Western arms have been critical to Ukraine’s success in stymieing Russia’s much larger and better equipped military — thwarting its initial efforts to take the capital and forcing Moscow to shift its focus instead to the eastern industrial Donbas region.

But as the war drags on and Russia bombards towns in its inching advance in the east, Ukraine has repeatedly pleaded for more and better weapons. Ukrainian President Volodymyr Zelenskyy has occasionally criticized the West for moving too slowly in shipping arms — and military analysts have said Russia is hoping to overrun the Donbas before any weapons that might turn the tide arrive.

Germany has come under particular fire, both at home and from allies abroad, that it isn’t doing enough.

German Chancellor Olaf Scholz told lawmakers that the IRIS-T SLM missiles it will send are the most modern air defense system the country has.