Ukraine's President in a statement said he's concerned about a possible full-scale war breaking out with Russia after the serious maritime clash between the two countries over the weekend.

"Officially, without tearing off chevrons, without 'green men,' Russian troops in large numbers attacked the ships of the Armed Forces of Ukraine," Poroshenko said on his website. He was referring to Russian special forces soldiers during the 2014 Russian annexation of Crimea who were not wearing any insignia on their green uniforms and Moscow had said they were Crimeans.

"And that is why I don't want anybody to think that it's a trifle. The country is under the threat of a full-scale war with the Russian Federation," Poroshenko said. The Ukrainian President also pointed to what he called a strong Russian military presence along the border with his country. He said the number of Russian tanks had tripled, citing intelligence reports but did not give any precise timescale for the buildup.

The statement comes a day after Ukraine’s Parliament voted to impose martial law in regions bordering Russia. While speaking to CNN, he said the Ukrainian government was considering limiting the entry of Russian citizens into Ukraine during the period of martial law. "One of the proposals to our chief of general staff and the chief of the border control is that (there) would be some limits for Russians to enter to Ukraine during this special period," Poroshenko said from Kiev, adding that a final decision would likely be made tomorrow.

The tensions with Russia see no sign of easing off  as the Ukrainian sailors captured by Russia during the naval skirmish have been sentenced to two months detention by a court in Crimea. The sentences were given to twelve of the 24 sailors being held by Moscow. The rest are to appear before the court in Simferopol on Wednesday.

Russia’s special forces – the FSB security arm has uploaded videos of some of the Ukrainian navy men making statements that they were aware of the "provocative nature" of the Ukrainian action.

Andriy Drach, said he had been on the Ukrainian gunboat with an order to sail from Odessa to Mariupol. "We were warned by the border service of the Russian Federation that we were violating Russian law. They had repeatedly asked us to leave the territorial waters of the Russian Federation," he said.

Ukraine's navy commander, Ihor Voronchenko, told Ukrainian TV that the men had given false statements under duress.

In reaction to the Ukrainian – Russian tensions, US President Donald Trump said he may cancel a meeting with Russian President Vladimir Putin at the G20 summit in Argentina. He told the Washington Post that the report coming from his national security team would be "very determinative".

"Maybe I won't have the meeting [with Mr Putin]. Maybe I won't even have the meeting. I don't like that aggression. I don't want that aggression at all," he said.

(The above story first appeared on LatestLY on Nov 28, 2018 08:37 AM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).