Ukrainian President Petro Poroshenko held a meeting with his top military and security chiefs amid talk of imposing martial law.
The Ukrainian parliament approved the introduction of martial law after Poroshenko reassured some sceptical lawmakers that it would not be used to curb civil liberties or delay elections scheduled for next year.
Russian state media said Poroshenko provoked the maritime incident as a means of delaying the election - and potentially to raise the stakes between President Trump and Putin, who are due to meet later this week.
"All hell broke loose", Yelchenko said, adding that Moscow's act of aggression breached several bilateral and global agreements.
Andriy Shevchenko, Ukraine's ambassador to Canada, said Monday the Russians had prepared for the escalation for months and now feel comfortable blockading the Kerch Strait in defiance of global condemnation.
"As President Trump has said many times, the United States would welcome a normal relationship with Russian Federation".
The FSB's Border Service in Crimea reported that three Ukrainian warships had illegally entered Russia's territorial waters, and were carrying out unsafe maneuvers, according to Russian state news agency TASS.
He said six Ukrainian sailors were wounded, a total of 24 were taken into custody, and the three ships were seized.
The Russians seized the three Ukrainian ships - the tugboat Yany Kapu and the two gunboats, the Berdiansk and Nikopol, according to the online publication The War Zone.
British Prime Minister Theresa May's spokesman, James Slack, said the incident was "further evidence of Russia's destabilising behaviour in the region and its ongoing violation of Ukrainian territorial integrity".More news: Prince Harry And Meghan Markle Are Moving To Frogmore Cottage
The Russians claimed that the ships entered a "prohibited area"; the strait had always been dual-use under a 2003 agreement between the two countries, but since invading and annexing Crimea Russia has claimed control over the strait.
A senior fellow at the pro-NATO Atlantic Council has said the U.S. should send naval ships into the Sea of Azov to guarantee it stays open after a skirmish between Russian and Ukrainian ships.
Foreign Affairs Minister Chrystia Freeland called on Moscow to immediately release Ukrainian sailors captured during the weekend skirmish and to ensure freedom of navigation through the Kerch Strait.
Kiev said its vessels did nothing wrong and has accused Russian Federation of military aggression.
But Russia called Ukraine's actions "dangerous". In the past, successful military action beyond Russia's borders has buoyed his popularity.
A Russian cargo ship blocked access to Ukrainian vessels by positioning itself beneath a bridge which Moscow has built since annexing Crimea in 2014.
The area is a strategic waterway for both countries which links the Black Sea to the Sea of Azov.
Several Russian fighter jets and combat helicopters were deployed to assist the blockade of the Kerch Strait.
Earlier on Sunday, Russia and Ukraine traded accusations over another incident involving the same three vessels, prompting Moscow to block passage through the Kerch Strait.
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. "At the time of the mission, we had small arms and large-calibre machine guns with ammunition on board", Lesovoy says in the video without specifying the name of the ship he was on.