Security measures in the Ukrainian capital Kyiv will be tightened after a spate of Russian ballistic missile attacks and threats of escalation, a city official said on Thursday.
Russia staged concerted air strikes on Ukraine's energy system last week in what Moscow said was part of a series of "revenge" strikes in response to Kyiv's bombardment of Russian regions.
Moscow has since increased its use of ballistic missiles, which are much faster than regular cruise missiles and harder to shoot down, to attack Ukrainian cities.
Serhiy Popko, head of Kyiv's military administration, said a city defense council would review the staging of public events and enhance security around large gatherings.
Decision made as a result of statements from Russia
He said the decision had been made because of Russian statements and Russian forces' use of missiles that reach their target within minutes of being fired.
He added that Russian agents "and other enemy elements" could be attempting to infiltrate the city.
"I ask Kyivans to remain calm. Do not panic. We are using preventative measures so that Kyiv and its residents are reliably defended," he said on Telegram.
Ukrainian officials regularly urge their Western allies to supply more air defense systems and munitions to thwart increasing Russian missile and drone attacks.