Russia has seized three Ukrainian naval vessels off the coast of the Crimean Peninsula in a major escalation of tensions between the two countries.
Two gunboats and a tug were captured by Russian forces. Ukraine says they were fired on and six crew were injured.
The countries blame each other for the incident. Ukraine’s government said it would declare martial law.
The crisis began when Russia accused the Ukrainian ships of illegally entering its waters.
The Russians placed a tanker under a bridge in the Kerch Strait – the only access to the Sea of Azov, which is shared between the two countries.
Ukrainian President Petro Poroshenko called an urgent meeting of his “war cabinet” over the incident, his spokesperson said.
Tensions have recently risen in the Black Sea and the Sea of Azov off the Crimean peninsula – annexed by Russia in 2014.
How did the crisis unfold?
In the morning, Ukraine’s Berdyansk and Nikopol gunboats, and the Yana Kapa tug, tried to sail from the Black Sea port of Odessa to Mariupol in the Sea of Azov.
Ukraine says the Russians tried to intercept the ships, ramming the tug. The vessels continued towards the Kerch Strait, but were prevented by the tanker.
Russia scrambled two fighter jets and two helicopters to the area. It accused the ships of illegally entering its waters and said the traffic had been suspended for security reasons.
The Ukrainian navy later said the boats had been hit and disabled as they tried to leave the area. It said the tug had been forced to stop.
Russia’s FSB later confirmed that one of its patrol boats had used force to seize the three Ukrainian vessels.
Ukraine said it had informed the Russians of its plan to move its ships through the sea to Mariupol.
What’s the background to this?
The shallow Sea of Azov lies east of Crimea, and south of the Ukrainian regions partially seized by pro-Russian separatists.
The two Ukrainian ports on its northern shore – Berdyansk and Mariupol – are key for exporting grain and produce such as steel, also for importing coal.
In 2003, Ukraine and Russia signed a treaty that defined the Sea of Azov as internal waters of the two countries. The treaty guaranteed free navigation to all Ukrainian and Russian vessels.
But Russia has recently begun inspecting all vessels going to or from Ukrainian ports. Earlier this month, the EU warned it would take “targeted measures” to address the issue.
“The situation in the Sea of Azov is damaging not only the Ukrainian economy, but also so many vessels that are flying the European Union member states’ flags,” EU foreign policy chief Federica Mogherini said.
The Russian inspections began soon after Ukraine detained a fishing vessel from Russian-annexed Crimea in March.
Moscow also says the inspections of the vessels are necessary for security reasons, pointing to a potential threat to the bridge from Ukrainian radicals.
More than 10,000 people have been killed in the eastern Donetsk and Luhansk regions since separatists moved against the Ukrainian state in April 2014.
Ukraine and the West accuse Russia of sending its troops to the region and arming the separatists.
Moscow denies this but says that Russian volunteers are helping the rebels.