Ukraine live updates: Putin puts nuclear deterrent on 'special alert'

Summary

• Vladimir Putin says he is moving Russia's nuclear deterrent to "special alert"
• He says it's a response to Nato "aggression"
• The announcement does not mean Russia intends to use the weapons
• The US has condemned the move as "unacceptable"
• Ukrainian troops are in control of Kharkiv, governor says, after Russian attack
• Ukraine claims 4,300 Russians have died in the whole invasion - this has not been verified
• The EU is to send weapons to Ukraine and has banned all Russian flights from European airspace
• A Ukrainian delegation will meet Russians on Belarus border for talks, Ukraine's president says
• And Germany pledges a massive hike in defence spending