Russia reopened the Kerch Strait near Crimea to shipping in the early hours of Monday morning after firing on and seizing three Ukrainian naval ships a day earlier, a move that triggered a dangerous new crisis between the two countries.
Russia's FSB security service said early on Monday its border patrol boats had seized two small Ukrainian armoured artillery vessels and a tug boat after opening fire on them and wounding several sailors. It is the most serious clash between Moscow and Kiev in years.
Russia had previously blocked the Kerch Strait near Russia-annexed Crimea to stop the ships from passing from the Black Sea into the Sea of Azov, saying the small flotilla had not notified it of its plans in advance and ignored warnings to stop while manoeuvring dangerously.
With relations still raw after Russia's 2014 annexation of Crimea and its backing for a pro-Moscow insurgency in eastern Ukraine, the incident risks pushing the two countries towards a wider conflict and is likely to renew Western calls for more sanctions on Moscow.
The Russian rouble opened 0.4 percent weaker against the dollar in Moscow, its lowest since mid-November.
Kiev, which denied its ships had done anything wrong, accused Russia of military aggression and asked for the international community to mobilise to punish Russia.
The U.N. Security Council will meet on the latest developments at the request of Russia and Ukraine later on Monday, diplomats said.
The European Union said in a statement it expected Russia to restore freedom of passage via the Kerch Strait and urged both sides to act with the utmost restraint to de-escalate the situation. A NATO spokeswoman issued a similar appeal to both sides.
Danish Foreign Minister Anders Samuelsen said on Twitter is country gave its full support to Ukraine.
"The development is very disturbing and can escalate," he said. Canadian Foreign Minister Chrystia Freeland said her country also condemned what she called Russian aggression and called on Moscow to release the captured vessels.
MARTIAL LAW IN UKRAINE?
A Reuters witness said the three Ukrainian naval vessels seized by Russia were being held at the Crimean port of Kerch. People in naval-style uniforms could be seen around the vessels, which bore no sign of damage, the witness said.
The FSB has said Russia has opened a criminal case in connection with what it said was the ships' illegal entry into Russia's territorial waters.
The FSB said three Ukrainian sailors were wounded in the incident and were getting medical care. Their lives were not in danger, it said.
The Ukrainian parliament is due to consider a proposal to impose martial law for 60 days later on Monday after Ukrainian President Petro Poroshenko met his top military and security chiefs on Sunday night.
The move may be unpopular in some quarters in Ukraine since it would restrict civil liberties and give state institutions greater power ahead of a presidential election next year which polls indicate Poroshenko would lose.
Russia annexed Crimea in 2014 and then built a giant road bridge linking it to southern Russia that straddles the Kerch Strait - a narrow stretch of water that links the Black Sea to the Sea of Azov, which is home to two of Ukraine's most important ports.
A bilateral treaty gives both Russia and Ukraine the right to use the Sea of Azov, which lies between them and is linked by the narrow Kerch Strait to the Black Sea.
Russia's control of Crimea, where its Black Sea Fleet is based, and of the bridge mean it is able to control shipping flows.
The crisis began on Sunday after Russia stopped the three Ukrainian ships from entering the Sea of Azov by placing a cargo ship beneath the bridge. Ukraine said a Russian ship had earlier rammed its tug boat in a failed to attempt to stop it.