"I would say the Kerch incident is a reminder that the less infrastructure you have, the less gas infrastructure you have bypassing Ukraine because of Nord Stream 2, the weaker the deterrent - deterrence is to Russian acts of military aggression", the official said in Brussels.
The Kremlin said Mr Poroshenko's latest announcement is an "absurd" attempt to inflame tensions.
"Yes, Berdyansk and Mariupol ports are partially unlocked".
Relations between the two neighbours have strained further following the November 25 incident in which Russian Federation fired upon and seized three Ukrainian naval vessels and their crews.
"The Kremlin is further testing the strength of the global order", Poroshenko said Saturday, alleging that Moscow is waiting to see whether the worldwide community will allow Russia to assert that the Sea of Azov and Black Sea are Russian territorial waters.
We recently saw how Russian Federation used military force against Ukrainian vessels and arrested the ships and the sailors and we call on Russian Federation to immediately release the ships and the sailors.
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Russian Federation and Ukraine have blamed each other, with Moscow closing the strait to all traffic and Ukrainian officials accusing Russian Federation of denying passage to Ukrainian commercial traffic in and out of Mariupol and Berdyansk.
According to the Ukrainian government, the Russian guards confronted the Ukrainian vessels and sparked a "lengthy standoff" that resulted in the Russians ramming into the other country's ships before taking the crews and departing from the scene. Moreover, during the preceding months, Russian Federation had systematically and aggressively obstructed Ukrainian and worldwide shipping in the Sea of Azov (see EDM, February 22, April 12, May 22, 31, June 11, 28, November 6).
Ukraine has also accused Russian Federation of blockading its ports on the Sea of Azov and urged Germany and other Western allies to boost their naval presence in the Black Sea to help deter Russian Federation from further aggression.
The incident was the most unsafe in years between the ex-Soviet neighbours, which have been locked in a confrontation since 2014 when Russian Federation annexed Crimea and supported an insurgency in eastern Ukraine.
Meanwhile, Ukrainian media said violence had continued in eastern Ukraine, where pro-Russian separatists seized areas of two border regions in 2014. He spoke Saturday said at an Ukrainian military event. "In response to Russia's aggressive actions, North Atlantic Treaty Organisation has substantially increased its presence in the Black Sea region over the past few years".
Poroshenko emphasized that "martial law does not mean the declaration of war", but a step toward strengthening Ukraine's defense. The naval clash further stoked tensions - and 24 Ukrainian seamen are still in Russian custody in Moscow.