A top Russian security official has issued a chilling warning to the West - promising the Kremlin will "fulfill threats" of a missile attack.
Security Council Deputy Chairman Dmitry Medvedev said Washington's decision not to send Ukraine rocket systems capable of striking Russian targets was "reasonable".
Medvedev wrote on his Telegram channel that Russia would have returned fire against Biden's "criminal decisions" at targets "not in Kiev at all".
He said: "Biden said that the U.S. will not supply Ukraine with missile systems capable of attacking Russia.
"Reasonable!
"Otherwise, when attacking our cities, the Russian Armed Forces would fulfil their threat and strike at the centres of these criminal decisions. Some of them are not in Kiev at all. What's next, there's no need to explain..."
It comes after President Biden announced today the US will not provide Kyiv with advanced long-range rocket systems that can reach Russia.
Ukrainian officials have been asking allies for longer-range systems including the Multiple Launch Rocket System, or MLRS, that can fire a barrage of rockets hundreds of miles away.
"We're not going to send to Ukraine rocket systems that strike into Russia," Biden told reporters after arriving back at the White House after a weekend in Delaware.
Biden did not rule out providing any specific weapons system, but instead appeared to be placing conditions on how they could be used. Biden and his team are working on a new package of military equipment and it is expected to be announced in coming days.
The MLRS was under consideration, but nothing with long-range strike capabilities outside of battlefield use, a senior administration official said.
The Ukrainian government has urged the West to provide it with more longer-range weapons in order to turn the tide in the war, now in its fourth month.
Biden wants to help Ukraine defend itself but has been opposed to providing weapons that Ukraine could use to attack Russia.
CNN and The Washington Post reported on Friday the Biden administration was leaning towards sending the MLRS and another system, the High Mobility Artillery Rocket System, known as HIMARS, as part of an upcoming military aid package.
Thousands of people have been killed in Ukraine and millions more displaced since the Russian invasion on Feb. 24, which Moscow calls a "special military operation."
Biden's administration and U.S. allies have been increasingly willing to give Ukraine longer-range weaponry, including M777 howitzers, as Kyiv battles Russian forces with more success than intelligence officials had predicted.
But U.S. intelligence has also warned about growing risks, particularly given a mismatch between Russian President Vladimir Putin's apparent ambitions and the performance of his military.
Ukraine has started receiving Harpoon anti-ship missiles from Denmark and self-propelled howitzers from the United States, Ukrainian Defence Minister Oleksiy Reznikov said on Saturday.
