Russia Releases Videos of Seized Ukrainian Sailors as Vladimir Putin Voices 'Serious Concern' Over Escalating Tensions

Russia's FSB security service has released video footage of three Ukrainian sailors captured in a naval clash between the two neighboring countries on Sunday.

The confrontation in the Sea of Azov has threatened to open a new front in the ongoing conflict between Russia and Ukraine, which has varied in intensity since Russian troops occupied Crimea in 2014.

According to The Associated Press, all three of the seamen who appeared on the FSB video admitted to violating the Russian border. It was not immediately clear if they were speaking honestly or were under duress, but the AP noted that one appeared to be reading his remarks from a teleprompter.

The videos were broadcast by Russian state media. The men identified themselves as Sergey Drach, a senior lieutenant from Ukraine's SBU counter-intelligence service, Sergey Tsybizov, a gunnery lookout and Captain Vladimir Lesov, a divisional commander. ABC News reported that their identities had not yet been confirmed.

All three were wearing Ukrainian military uniforms and appeared to be reciting memorized speeches. The men said they deliberately ignored repeated requests by the Russian coast guard to stop.

"We consciously ignored requests by radio to stop," Lesov told the camera. "I realized that the actions of the Ukrainian navy ships was of a provocative character."

The three men are among 23 detained by Russian forces Sunday. Three Ukrainian vessels—two gunboats and one tug—were sailing through the Kerch Strait off the Crimean Peninsula when they were confronted by Russian warships, helicopters and fighter jets.

Their way through the strait was blocked by a Russian tanker placed under the new bridge connecting Russia with Crimea, which was completed earlier this year. The Russian ships tailed the Ukrainians and rammed one of the ships.

Russian forces then opened fire, disabling the ships and wounding six Ukrainians. Special forces then stormed and took control of the boats.

Confrontations in the Sea of Azov have been on the rise since Russia seized Crimea in 2014. The Kerch Strait is the only way for Ukrainian ships to travel between its Black Sea and Sea of Azov coastlines. Though the waters were designated as shared by a 2003 treaty, Russia has been extending control over the route with an increasingly aggressive stance toward transiting vessels.

On Monday, Ukrainian President Petro Poroshenko declared martial law in territories bordering Russia, Belarus and Moldova's breakaway republic of Trans-Dniester. Poroshenko also said that he had received intelligence of a ground offensive being prepared by the Kremlin, raising fears of a larger-scale clash between the two neighbors.

Russian President Vladimir Putin said Monday he was "seriously concerned" about the implementation of martial law along the border. Putin spoke with German Chancellor Angela Merkel and asked her to influence Kiev and avoid escalation, a Kremlin statement explained.

Putin reportedly told Merkel that she could be vital in helping "dissuade [the Ukrainian authorities] from further reckless acts," the AP reported.