President Donald Trump is noticeably silent after Russia was accused of aggression on Sunday by the Ukrainian government, which will meet Monday to vote on implementing martial law, following Russia’s seizing of three Ukrainian navy ships and 24 sailors.
The president, who has previously blamed former President Barack Obama for Russia's annexation of the Crimean Peninsula, has so far released no statement or tweet on the latest incident.
The incident on Sunday marked a major escalation in tensions between the two former Soviet Republics. NATO has called for calm, and an emergency United Nations Security Council meeting will be convened Monday to discuss the issue.
Ukraine said the small gunboats Berdyansk and Nikopol and the tugboat Yany Kapu were attacked by Russian forces after entering the Kerch Strait, en route to the city of Mariupol, on Sunday.
Video of the incident released by Ukrainian officials appeared to show a Russian ship ramming the Ukrainian tugboat.
All 24 sailors aboard the three boats were detained by Russia, state news agency RIA reported on Monday, citing sources in Crimea's security agencies. Three of the sailors were now in hospital, it added.
The Kerch Strait is a narrow and shallow stretch of water between the Crimean Peninsula and Russia, just 2-3 miles wide at one point.
It is important to Ukraine’s economy as it provides ships with access to the Black Sea, CNN noted.
Both Ukraine and the United States have accused Russia of interfering with international shipping in and out of the Kerch Strait for months.
On Sunday, officials from Russia and Ukraine blamed one another for aggressive behavior in the incident.
Ukraine and Russia offered conflicting accounts of the incident, each accusing the other side of violating the laws of the sea. A 2003 agreement confirms the Azov Sea and the Kerch Strait as domestic waters of Russia and Ukraine.
Russia's Federal Security Service (FSB) Border Service in Crimea reported that three Ukrainian warships had illegally entered Russia's territorial waters, and were carrying out dangerous maneuvers, according to Russian state news agency TASS.
"They did not respond to legitimate demands by the ships and boats of Russia's FSB Border Guard Service escorting them to stop immediately and performed dangerous maneuvers," the FSB said, according to TASS.
TASS said three Ukrainian servicemen were injured and received medical care from the Russians.
But according to the Ukrainian navy, the Russian ships "carried out openly aggressive action" against the Ukrainian ships.
President Poroshenko's office described the Russian action against the Ukrainian navy ships as "an act of aggression aimed at deliberately escalating the situation in the waters of the Sea of Azov and the Kerch Strait," and called for international condemnation of Moscow and the imposition of new sanctions.
Ukrainian Interior Minister Arsen Avakov tweeted a video that he says shows the Russian ship deliberately colliding with one of the Ukrainian vessels.
The video appears to be shot from on board a Russian vessel. A commander can be heard speaking Russian, swearing and ordering his crew to "slam him from the right," "squeeze him" and finally warning those on board to "hold on" before the moment of impact.
It's unclear how Avakov obtained the video. Similar clips were released by Russian state media but those did not show the actual collision.