The US is to give $400m (£333m) more in military aid to Ukraine to boost Kyiv's ammunition stocks depleted during its ongoing high-intensity war with Russia.
Secretary of State Antony Blinken said this included high-precision Himars artillery rockets and howitzers "which Ukraine is using so effectively".
The US is also sending tactical bridges ahead of Ukraine's expected offensive.
The delivery of such equipment allowing armoured vehicles to cross rivers and ditches comes as a number of Ukrainian military officials and experts have suggested the operation could be launched in the coming weeks.
Meanwhile, Moscow on Friday maintained its months-long assault on Bakhmut, with Russian mercenaries claiming that they have "practically encircled" the city in the eastern Donetsk region.
In its latest news bulletin, Ukraine's military said Russian troops continued their efforts to encircle the city - but "numerous attacks were repelled" in the past 24 hours.
Separately, partial evacuation was on Thursday ordered in the north-eastern city of Kupiansk, Kharkiv region, which was liberated from the Russian occupation last September.