"The Berdyansk and Mariupol ports have been partially unblocked," Ukraine's infrastructure minister Volodymyr Omelyan said.
Ukraine and Russia have been at loggerheads after the Russian Navy last week seized three Ukranian ships and took at least 24 sailors into custody. Russia has refused to free the sailors and hasn't released the ships amid sustained Western pressure.
"We can see how instead of thirty soldiers, who were invited to arrive at a military commission in order to participate in exercises, 165 soldiers came - with backpacks and ready to defend Ukraine at any time," Ukrainian President Petro Poroshenko said.
Ukranian forces conducted drills in the north of the capital bordering Russia as tensions between the two countries continued unabated. Ukraine had imposed martial law on November 26th after the skirmish with Russian forces in the Sea of Azov.
Canadian armed forces joined Ukraine's land forces during the drill. Canadian commander Jean-Marc Lanthier said Canada stands shoulder to shoulder with Ukraine.
However, in the past two days, tensions have eased as Russia began to open the sea route.
"Ships are coming and going through the Kerch Strait towards Ukrainian ports... movement has been partially restored," a Ukranian ministry statement said.
Meanwhile, EU nations including Poland called for tougher sanctions on Russia amid the standoff.
Polish foreign minister Jacek Czaputowicz said: If they are ready to use more than ten military ships and the whole military mechanism against two Ukrainian motor boats and one tug, can you imagine what they are able to use in the Baltic Sea in order to protect Nord Stream 2?"
Last week, Ukrainian state border guards allowed only Ukrainian citizens to cross the border into Crimea. Ukraine had earlier barred entry of Russian men aged between 16-60 years from entering its territory.
President Petro Poroshenko had said banning Russian men was important for stopping a full-scale invasion.
Ukranian forces conducted drills in the north of the capital bordering Russia as tensions between the two countries continued