Ukraine's president demanded Monday that Russia immediately release Ukrainian sailors and vessels seized in a standoff around Crimea that sharply escalated tensions between the two countries and drew international concern.
The two neighbours have been locked in a tense tug-of-war since Russia's 2014 annexation of Crimea, but the incident late Sunday, in which Russian coast guard ships fired on Ukrainian navy vessels near the Kerch Strait, directly pitted the two militaries against each other, placing them on the verge of an open conflict.
The Ukrainian navy said six of its seamen were wounded when Russian coast guards opened fire on three Ukrainian ships near the Kerch Strait and then seized them.
Russia said that three Ukrainian sailors were lightly injured and given medical assistance.
Ukraine's president, Petro Poroshenko, chaired an emergency meeting of his Cabinet early Monday and asked parliament to introduce martial law for two months in response to what he described as Russian aggression.
"We consider it as an act of aggression against our state and a very serious threat," the president said.
"Unfortunately, there are no 'red lines' for the Russian Federation."
Ukrainian Foreign Minister Pavlo Klimkin told reporters later Monday that Kiev believes that what happened near the Kerch Strait was no accident but "deliberately planned hostilities."
They also include a plethora of vaguely worded steps such as the "strengthening" of anti-terrorism measures and "information security."
NATO said Stoltenberg expressed the US-led military alliance's "full support for Ukraine's territorial integrity and sovereignty, including its full navigational rights in its territorial waters under international law."
"While planning that provocation, Ukraine had undoubtedly hoped to get additional benefits from the situation, expecting the US and Europe to blindly take the provocateurs' side."
President Vladimir Putin's spokesman, Peskov, said that Poroshenko's initiative to introduce martial law "clearly smacks of electoral intrigues."