Russia condemns the implementation, saying martial law will escalate the conflict that has killed about 10,000 people.
A 30-day period of martial law has taken effect in 10 of Ukraine’s 27 regions on Wednesday, with President Petro Poroshenko saying it aims to prevent an all-out Russian invasion.
The measure, which affects the regions closest to Russia’s military bases – the first ever martial law in the country’s history – was approved by parliament on Monday, a day after a clash between Ukrainian and Russian forces in the Sea of Azov.
The largely symbolic legislation was activated after Poroshenko and Andriy Parubiy, chairman of Verkhovna Rada – the Ukrainian parliament – signed and published it in the government newspaper, Uryadovy Courier.
The Kremlin has condemned the development, saying martial law will escalate the conflict that saw Moscow seize three Ukrainian ships and capture 24 crew members off the coast of the Russian-annexed Crimean peninsula.
On Wednesday, Russia’s Southern Military District spokesperson, Vadim Astafyev, told Interfax news agency that a fourth S400 surface-to-air missile battalion would soon be deployed to Crimea.
The annexed peninsula already has three such missile installations, which are capable of shooting down up to 36 aircraft at a range of 400km. The new missiles will be operational by the end of the year, according to Russia’s Ria news agency.
Ukraine has yet to comment on the development.
Volodymyr Fesenko, director of the Penta centre for political studies, told Al Jazeera martial law was “for now more like a preventive measure”.
But in case of any “manifestations of the Russian aggression”, Ukraine would be able to respond militarily, he said.
“It will not affect the day-to-day life of ordinary people,” said Fesenko.