German Chancellor Olaf Scholz on Wednesday said his country will supply Ukraine with modern anti-aircraft missiles and radar systems, stepping up arms deliveries amid criticism that Germany isn’t doing enough to help Kyiv fend off Russia.

Scholz told lawmakers that the government has decided to provide Ukraine with IRIS-T missiles developed by Germany together with other NATO nations.

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He said Germany will also supply Ukraine with radar systems to help locate enemy artillery.

The announcement comes as Ukrainian forces are engaged in a grinding battle for the eastern industrial region of the Donbas. Following a series of setbacks in the weeks after their invasion, Russian troops switched their focus to the Donbas and are bent on capturing the parts of the region not already controlled by Moscow-backed separatists.

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In the Donbas, Russian forces have seized half of a key eastern Ukrainian city in a “frenzied push,” the Mayor Oleksandr Striuk said Tuesday. Serhiy Haidai, governor of the larger Luhansk region, meanwhile, said that most of the city, Sievierodonetsk, was under Russian control, though he added that fierce fighting continued and the city wasn’t surrounded.

Military analysts have said the battles in the Donbas are a race against time: The Kremlin is hoping for a victory before more Western arms arrive to bolster Ukraine’s defences.

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The West is hoping to tilt the balance. President Joe Biden said Tuesday the U.S. will provide Ukraine with the more advanced rocket systems that its leaders have asked for. In an essay published in The New York Times, Biden said the rocket systems will enable Ukraine “to more precisely strike key targets.”

U.S. officials, speaking before Biden’s announcement on condition of anonymity, said Washington will send Ukraine a small number of high-tech, medium-range rocket systems. The rockets could be used both to intercept Russian artillery and to take out Russian positions in towns where fighting is intense, such as Sievierodonetsk.

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The announcements come amid claims at home and abroad that Germany has been slow to provide Ukraine with the weapons it needs to defend itself against Russia.