Vladimir Putin has issued a grim ultimatum to Donald Trump ahead of a threatened 'systematic' blitz on Kyiv: get Americans out, now. 

Russian Foreign Minister Sergei Lavrov phoned his counterpart Marco Rubio on Monday to warn that Moscow would launch 'systematic and consistent strikes' against the Ukrainian capital, urging him to evacuate US citizens and diplomats. 

Rubio told reporters that Putin had personally requested the warning be passed to Trump, and confirmed he had done so.  

Speaking aboard a flight to Armenia, Rubio said there were no negotiations ongoing with Ukraine but that Washington stood ready to 'play a constructive and helpful role if that opportunity presents itself.'  

The Kremlin had earlier released a statement warning that the strikes would 'target decision-making centers and command posts.' 

'We are notifying foreign citizens, including the personnel of diplomatic missions and international organizations of the need to leave the city as soon as possible,' the Kremlin added.

Ukrainian Foreign Minister Andrii Sybiha urged Kyiv's allies not to cave to 'Russian blackmail.'  

Katarina Mathernova, the European Union's ambassador to Ukraine, vowed the 27-nation bloc was staying put. 

'Russia wants fear, panic, isolation of Ukraine. It will not work. The EU is not going anywhere. We are staying in Kyiv. We are staying with Ukraine,' she said. 

A spokesperson for France's foreign ministry was equally defiant: 'We're used to Putin's threats. It is out of the question to evacuate.' 

Russian strikes on Kyiv over the weekend killed four people and injured around 100 more. 

Moscow claimed those strikes, and any to come, were retaliation for what it called a deliberate Ukrainian attack on a student dormitory in the Russian-occupied city of Starobilsk on Friday. 

The Kremlin said 21 people were killed in that strike, prompting Putin to order retaliation. Ukraine's military countered that it had hit an elite Russian drone unit in the area, not civilians.  

Russia had issued a similar evacuation call earlier this month, threatening massive strikes on central Kyiv if Ukraine disrupted a military parade on Red Square. 

Russian attacks killed four people and wounded more than a dozen others across eastern Ukraine on Monday, local authorities said. 

A strike on the town of Dergachi in the northeastern Kharkiv region killed two men, aged 68 and 25, and wounded nearly two dozen others, regional governor Oleg Synegubov said.

Russian forces occupied swathes of the Kharkiv border region when they invaded in 2022, but were pushed back months later in a Ukrainian offensive that embarrassed the Kremlin.

A separate attack on Kramatorsk in Ukraine's eastern Donetsk region killed two people, the city's mayor Oleksandr Goncharenko said on Facebook.

Russia launched its full-scale offensive in February 2022, and the conflict has since spiraled into Europe's deadliest since World War II. 

Kyiv has spent the years since lobbying allies to help push Putin's forces back, and pressing Washington in particular to expand missile production, so far to no avail. 

Volodymyr Zelensky admitted on Monday that Ukraine had made little headway in talks with Washington on expanding missile defense production and was now turning to Europe to fill the gap. 

'Unfortunately, there has been no progress for a long time with America regarding the expansion of anti-ballistic missile production,' he said. 

'We are trying to accelerate this work in Europe, the production of our own anti-ballistic systems on the continent in sufficient quantities.'

Zelensky said Ukraine was continuing to press Washington for help and insisted US leadership remained vital.