The US says more military assistance to Ukraine worth $2.2bn (£1.83bn) will have long-range missiles capable of doubling its attack capacity.
It gets the entire amount of military help given to Ukraine to almost $29.3bn (£24.31bn) since February 2022.
US to help Ukraine in war with new package:
The package contains ground-launched small-diameter bombs (GLSDB), which can strike targets 150km (93 miles) away.
But officials denied being drawn on the belief that the munitions could be used to batter areas of annexed Crimea.
“When it is for Ukrainian plans on operations, apparently that is their decision,” Pentagon representative Brig Gen Pat Ryder told journalists.
“This offers them a longer-range capability, long-range fires power, that will allow them to execute operations in defence of their nation and take back their sovereign domain, Russian-occupied regions.”
Russia illegally annexed the Crimean Peninsula in 2014 and believed it was the domain of its territory. But it has come under intermittent fire from Ukrainian armies in recent months.
Western countries have often ruled out delivering Ukraine with offensive weapons – such as fighter planes – which it could use to attack Russia itself.
In a tweet, Ukrainian President Volodymyr Zelensky thanked the US and President Joe Biden for the extra help.
“The better long-range our weapons are, and the more mobile our militaries are, the sooner Russia’s ruthless aggression will terminate,” Mr Zelensky noted. “Together with [the US], we stand against terror.”
Earlier, Ukraine’s most extended-range weapon was the Himars rocket system, which can strike targets up to 80km (50 miles). Kyiv used the system to devastating impact during its counter-offensive in the south and east last year.
The GLSDB even gives Ukraine forces the capability to hit anywhere in the Russian-occupied Donbas, Zaporizhzhia and Kherson areas.
It also lets Ukraine risk Russian supply lines in the east.
Manufactured by Boeing and Saab, GLSDB is a gliding missile with a small bomb bound, capable of hitting a target within one metre of its position.