MOSCOW (AP) - The Ukrainian navy said Sunday that Russia's coast guard opened fire on and seized three Ukrainian vessels and wounded two crew members in the Black Sea following a tense standoff off the coast of the Crimean Peninsula.
Ukraine's navy said that two of its vessels were struck and that Russian coast guard crews boarded them and a tugboat and seized them. The Russian Federal Security Service, known as the FSB and which is in charge of the coast guard, said that it has evidence that Ukraine was responsible for the clashes.
"There is irrefutable evidence that Kiev prepared and orchestrated provocations ... in the Black Sea," the FSB said in a statement. "These materials will soon be made public."
There have been growing tensions between Ukraine and Russia, which annexed Crimea from Ukraine in 2014 and has steadily worked to increase its zone of control around the peninsula.
Earlier Sunday, Russia and Ukraine traded accusations over another incident involving the same three vessels, prompting Moscow to block passage through the Kerch Strait.
The Ukrainian vessels apparently wanted to travel through the strait to other ports in Ukraine, and Ukrainian authorities said they had given advance notice to the Russians.
The tensions began Sunday morning. Russia's coast guard said that the three Ukrainian vessels made an unauthorized crossing through Russian territorial waters, while Ukraine alleged that one of its boats was rammed by a Russian coast guard vessel.
The Kerch Strait is a narrow body of water nestled between Crimea and the Russian mainland.
The incident began after the Ukrainian navy claimed a Russian coast guard vessel rammed one of its tugboats, which was traveling with two Ukrainian navy artillery boats from Odessa on the Black Sea to Mariupol in the Sea of Azov, via the Kerch Strait.
"Russian coast guard vessels ... carried out openly aggressive actions against Ukrainian navy ships," the Ukrainian navy statement said. It said a Russian coast guard ship damaged the tugboat's engine, hull, side railing and a lifeboat.
The statement added that Russia had been informed in advance about the planned journey.
Russia then blocked off the strait.
The Kerch Strait is the only passage into the Sea of Azov beyond it. The strait is crossed by the recently completed Kerch Bridge, connecting Crimea to Russia. Transit under the bridge has been blocked by a tanker ship, and dozens of cargo ships awaiting passage are stuck.
Russia has not given any indication of how long it will keep the strait blocked off, but a long-term closure to civilian traffic would amount to an economic blockade of Ukrainian cities on the Azov coast. And Russia's Black Sea Fleet greatly outmatches the Ukrainian navy.
Ukrainian cities on the Sea of Azov include strategically vital centers such as Mariupol - the closest government-controlled city to Donetsk and Luhansk, the breakaway regions of eastern Ukraine controlled by Russia-backed separatists.
The FSB told Russian news agencies Sunday after the first incident that the Ukrainian ships held their course and violated Russian territorial waters. The FSB accused the Ukrainian navy of staging a provocation against Russia.
"Their goal is clear," an FSB statement said - "to create a conflict situation in the region." The statement didn't mention ramming a Ukrainian tugboat.
Though a 2003 treaty designates the Kerch Strait and Sea of Azov as shared territorial waters, Russia has been asserting greater control over the passage since 2015.
The Ukrainian Foreign Ministry said in an earlier statement that Russia's actions were a violation of the U.N. Charter and international law, and pledged to "promptly inform our partners about Russia's aggressive actions."
"Such actions pose a threat to the security of all states in the Black Sea region," the statement said, "and therefore require a clear response from the international community."
Dmitry Kiselyov, a commentator on the state-controlled Rossiya channel, told viewers of his Sunday evening news program that Ukrainian President Petro Poroshenko - encouraged by the U.S. - is looking to pick a fight with Russia in the Black Sea.
The talk show host also said that the U.S. talked Poroshenko into staging a provocation against Russia as a means to disrupt the upcoming meeting between Presidents Vladimir Putin and Donald Trump at this week's Group of 20 summit in Argentina.
"What is happening now at the (Kerch) bridge threatens to turn into a very unpleasant story," Kiselyov warned.