In Ukraine, where armed forces were on full combat alert, President Petro Poroshenko sought parliament's approval to impose martial law from Wednesday to strengthen national defences against possible "invasion" by Russian Federation.
Poroshenko declared 30 days of martial law; he originally proposed 60 days.
"The National Security and Defense Council's decision concerning "emergency measures to ensure Ukraine's state sovereignty and independence and declare martial law in Ukraine" is hereby enacted", President Pyotr Poroshenko announced on his website.
The Ukrainian Foreign Ministry said in an earlier statement that Russia's actions were a violation of the UN Charter and worldwide law, and pledged to "promptly inform our partners about Russia's aggressive actions".
"I condemn Russian use of force in Azov Sea", Donald Tusk, the EU Council president, added.
"In the name of global peace and security, Russian Federation must immediately cease its unlawful conduct and respect the navigational rights and freedoms of all states", she said during the U.S. Security Council meeting.
The crisis unfolded on Sunday as two Ukrainian small warships and a tugboat were heading through the Kerch Strait, a narrow waterway that gives access to the Sea of Azov that is used by Ukraine and Russian Federation.
But Washington's special envoy to Ukraine, Kurt Volker, took to Twitter Monday: "Russia rams Ukrainian vessel peacefully traveling toward a Ukrainian port. Russia seizes ships and crew and then accuses Ukraine of provocation???"
The FSB said three Ukrainian sailors were wounded in the incident and were getting medical care.
"This is a very risky provocation, which requires particular attention and a special investigation", Russian presidential spokesman Dmitry Peskov told state media.
UCF Knights Hit Top 10 in College Football Playoff Rankings
The top-ranked conference champion from the Group of 5 leagues automatically earns a spot in one of the access bowl games. The UCF Knights football team is undefeated, after beating Cincinnati in a primetime game at home Saturday, 38-13.
But he rowed back from an earlier proposal to impose martial law for two months after several lawmakers voiced concern and he said his decree did not foresee any restrictions on the rights and freedoms of citizens or the introduction of censorship. "Since 2014, all allies have condemned Russia's aggressive actions in Crimea and Eastern Ukraine", Stoltenberg said during press-conference.
Russian fighter jets fly over vessels as part of operations preventing three Ukrainian navy ships from entering the Sea of Azov, Nov. 25, 2018.
When the Ukrainian ships appeared in the waters of the Kerch Strait, locals saw aircraft n flying over the Kerch Bridge.
"They want to cut off our seaports on the Azov Sea and it's extremely important for the exports of Ukrainian steel and commercial products", said Shevchenko.
Referring to Sunday's incident, Polyansky said Ukraine had planned the "provocation" in advance with the coordination of western states, which he said had given the Ukrainian government "carte blanche".
Moscow claimed that the Ukrainian ships had illegally entered Russian territorial waters.
Turkey stressed that as a country sharing a Black Sea coast "passage through the Kerch strait should not be blocked", and called for an avoidance of any actions likely to endanger stability and peace in the region.
"The episode in the Black Sea and Sea of Azov, and the feeble Western reaction, suggests that the aggressor will feel empowered".
Martial law would "in the event of an invasion allow us to respond quickly, to mobilise all resources as quickly as possible", he said.
Mariupol is close to the region of eastern Ukraine controlled by Russian-backed separatists in a conflict that has caused at least 10,000 deaths since 2014.