Ukraine on Monday declared the imposition of martial law in its border regions for a month from November 28, AFP reported. The move came a day after Russia seized three of its navy vessels off the Crimean Peninsula.

Ukraine’s parliament supported President Petro Poroshenko’s request to introduce martial law, with 276 lawmakers voting in favour. A minimum of 226 votes was required to pass the motion.

Ukraine said six of its soldiers were injured after a Russian border guard vessel allegedly rammed one of its tugboats in the Kerch Strait, a narrow body of water that gives access to the Sea of Azov and is used by both nations. Russia had annexed the Crimean Peninsula in 2014. However, Russia claimed it had been forced to act as Ukrainian ships illegally entered its waters to “intentionally” provoke a conflict.

The martial law will be in effect in five regions bordering Russia, two regions along Moldova’s breakaway Transnistria region, and three areas on the coast of the Black Sea and the Sea of Azov, BBC reported. It will give the Ukrainian government the power to restrict public rallies and regulate the media.

Poroshenko said martial law was required to shore up the country’s defence and warned of an “extremely serious” threat of a land invasion in light of Russia’s attack, Reuters reported. “Russia has been waging a hybrid war against our country for a fifth year,” he said. “But with an attack on Ukrainian military boats it moved to a new stage of aggression.”

Intelligence data indicated there was an “extremely serious threat” of a land-based operation by Russia, Poroshenko said. “I have a document of intelligence in my hands... here on several pages is a detailed description of all the forces of the enemy located at a distance of literally several dozens of kilometres from our border,” he said. “Ready at any moment for an immediate invasion of Ukraine.”

However, Russian President Vladimir Putin expressed “serious concern” over the declaration, AFP reported. In a telephone conversation with German Chancellor Angela Merkel, Putin said he hoped “Berlin could influence the Ukrainian authorities to dissuade them from further reckless acts”.

“It was emphasized that the Ukrainian leadership bears full responsibility for creating another conflict situation and for risks associated with it,” the Kremlin press service said according to the TASS news agency. “All of this was evidently undertaken with Ukraine’s election campaign in mind.” TASS said that it was Merkel who initiated the call with Putin.

US criticises Russia

United States Secretary of State Mike Pompeo called Russia’s actions “a dangerous escalation and a violation of international law” and urged both countries to show restraint. “The United States condemns this aggressive Russian action,” he said in a statement. “We call on Russia to return to Ukraine its vessels and detained crew members, and to respect Ukraine’s sovereignty and territorial integrity.”

Washington’s envoy to the United Nations Nikki Haley said Russia’s actions were an “outrageous violation of sovereign Ukrainian territory” and that sanctions on Moscow would remain in place. Haley said her statement “reflects the concerns at the highest level” having earlier spoken with Pompeo and President Donald Trump.

The European Union, Britain, France, Poland, Denmark, and Canada also condemned the Russian “aggression”.