Nuclear weapons would only be used in the event of an "existential threat" to Russia: Putin

Putin's top spokesman refused to rule out the use of nuclear weapons in an interview with CNN on Tuesday, saying they would only be used in the event of an "existential threat" to Russia

The US Pentagon denounced the statement as reckless, saying "it's not the way a responsible nuclear power should act"

The Russian advance continues to stall, according to Western intelligence agencies, as Putin's troops take up defensive positions in their effort to encircle large Ukrainian cities

Around 100,000 residents of Mariupol remain trapped in the strategic southern port city that Russia has focused its efforts on capturing

Around 7,000 Mariupol residents were rescued on Tuesday, President Zelensky said in his nightly Facebook address

The US is expected to announce further sanctions on Moscow when President Biden travels to Brussels for talks with Nato and G7 leaders on Thursday

Zelensky is expected to address the gathering via remote teleconference

Ukrainian officials say he will use the opportunity to call for more air defence systems