Martial law was imposed in Ukraine for 30 days as president Petro Poroshenko warned of the “extremely serious” threat of a Russian land invasion.
The parliament voted in favour of the measure on Monday night in response to the capture of three Ukrainian navy vessels and twenty-three crew members by Russian ships near the Kerch Strait.
Russia’s actions were also condemned at emergency meeting of the United Nations Security Council, where US representative Nikki Haley described the incident as an “outrageous violation of sovereign Ukrainian territory.”
The secretary-general of Nato, Jens Stoltenberg, also said there was “no justification” for the seizure of the Ukrainian ships and sailors.
Meanwhile there there violent protests in Kiev and demonstrations outside Russian embassies across the world, including in London, Washington DC and Brussels.
It marked an escalation of tensions that have soared since Russia annexed Ukraine’s Crimean Peninsula in 2014 and backed a separatist insurgency in eastern Ukraine.
Ukraine said its vessels were heading to the Sea of Azov in line with international maritime rules, while Russia charged that they had failed to obtain a permission to pass through the Kerch Strait separating Crimea from the Russian mainlan
It is the only passage between the Black Sea and the Sea of Azov. It is spanned by a 11.8 mile bridge that Russia completed this year.
While a 2003 treaty designates the Kerch Strait and Sea of Azov as shared territorial waters, Russia has sought to assert greater control over the passage since the annexation of Crimea.
The seizure of the Ukrainian ships followed a tense situation in which the three Ukrainian vessels were manoeuvring near the Kerch Strait for hours shadowed by Russian coast guard boats.
Following the capture of the Ukrainian ships on Sunday, Russia closed the Kerch Strait for sea traffic by positioning a tanker under the bridge spanning it. It reopened the route early Monday.
If you want to read how the situation developed, please read our live coverage below.
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Hello and welcome to The Independent's coverage of the rising tensions between Russia and Ukraine after Moscow seized three Ukrainian boats on Sunday, much to the alarm of the international community.
It came following a shoot-out in the Black Sea near the Crimean peninsula, prompting the UN Security Council to call an emergency meeting.
The Russian coastguard opened fire on two artillery boats and a tug belonging to Ukraine which it claimed had made an unauthorised passage through Russia’s waters.
Two of the craft, the Berdyansk and the Nikopol, were damaged.
The three Ukrainian naval vessels seized by Russia off the coast of Crimea are being held at the Black Sea peninsula's port of Kerch, a witness has said.
People in naval-style uniforms could be seen around the vessels, which bore no sign of damage, the witness said.
A senior German official is calling on Russia and Ukraine to deescalate tensions after Russian coast guard ships fired on Ukrainian navy vessels.
Michael Roth, a deputy foreign minister, tells radio the matter is "very dangerous — the last thing we need is a further escalation in relations between Russia and Ukraine".
Mr Roth says he did not have any information of his own on the incident "but it is clear that Russia, in accordance with international law, must ensure unhindered access to Ukrainian harbors in the Sea of Azov."
He added that "both sides must now deescalate" and avoid a spiral of tensions that "could ultimately lead to terrible consequences".
Turkey has said it is worried by reports of Ukrainian ships had been fired on that shipping in the Crimean peninsula should not be obstructed.
"As a country sharing a Black Sea coast, we underline that passage through Kerch Strait should not be blocked," Turkey's foreign ministry said in a statement.
It also called for avoiding steps that could endanger stability and peace in the region.
Here's all you need to know about the politics of Russia's manoeuvres in the Black Sea, and why it could prove convenient to both Moscow and Kiev.
Russia has breached international rules through its aggressive behaviour towards Ukrainian naval ships in the Azov Sea, Poland's Ministry of Foreign Affairs said on Monday.
"With full force we condemn Russia's aggressive behaviour and we call on (the country's) leadership to respect international law," the ministry said in a statement.
Russia reopened the Kerch Strait near Crimea to shipping in the early hours of Monday morning.
Moscow had previously blocked the Kerch Strait near Russia-annexed Crimea to stop ships from passing from the Black Sea into the Sea of Azov.
The Kremlin said a small flotilla of three ships had not notified it of its plans in advance and ignored warnings to stop while manoeuvring dangerously.
Here's video footage of a Russian vessel ramming the Ukrainian tugboat - one of three ships seized by Russian authorities in the Black Sea.
Russia's foreign ministry has accused Ukraine of deliberately provoking an incident in the Kerch Strait.
Moscow will summon a senior Ukrainian diplomat to complain about the incident, foreign ministry spokeswoman Maria Zakharova said on state television.
Nato spokeswoman Oana Lungescu has said the milittary alliance is calling for "restraint and de-escalation" overt the incident in the Black Sea.
She said Nato supports Ukraine's "navigational rights in its territorial waters" and calls on Russia "to ensure unhindered access to Ukrainian ports in the Azov Sea, in accordance with international law".
Nato headquarters declined to say whether its ambassadors would meet to discuss the incident, but the alliance is in contact with Ukrainian authorities.
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