Ukraine on Monday imposed martial law in parts of the country to fight what its president called "growing aggression" from Moscow, reports The Associated Press.
The move followed Sunday’s naval confrontation off the Crimean Peninsula in which Russia fired on and seized three Ukrainian vessels amid renewed tensions between the neighbors.
Ukrainian President Petro Poroshenko asked lawmakers in Kiev to institute martial law, and the proposal was overwhelmingly approved by parliament after a five-hour debate.
Martial law will be imposed for 30 days in only 10 of Ukraine's 27 regions - those bordering Russia, Belarus and Moldova's pro-Moscow breakaway republic of Trans-Dniester. The locations chosen were ones that Poroshenko identified as potentially in the front line of any Russian attack. The capital of Kiev is not under martial law.
Poroshenko said it was necessary because of intelligence about "a highly serious threat of a ground operation against Ukraine." He did not elaborate.
"Martial law doesn't mean declaring a war," he said, according to AP. "It is introduced with the sole purpose of boosting Ukraine's defense in the light of a growing aggression from Russia."
Ukraine's Defense Ministry already announced earlier in the day that its troops were on full combat alert in the country.
Earlier on Monday, at a UN Security Council meeting to discuss Sunday’s incident, US Ambassador Nikki Haley urged Russia to "immediately cease its unlawful conduct" in the Black Sea.
The incident is threatening to reignite the tensions between Ukraine and Russia, which intensified in 2014 when Russia occupied and annexed the Crimean Peninsula from Ukraine.