Those tensions have prompted international troops, including Canadians, to set up in Ukraine and Eastern Europe to both train the Ukrainians to protect themselves and help deter Russia from trying to annex further territories in the area adjacent to Europe.
But over the weekend, festering tensions between the two countries culminated in Russia ramming and then seizing three Ukrainian vessels in the Kerch Strait off the Crimean Peninsula, in what marks the most dangerous escalation of the conflict at sea so far.
Russia says the Ukrainian ships violated its territory.
Ukraine says it has the right to unimpeded access to the waterway in question as a key shipping route, and wants the international community to levy a fresh round of sanctions against Russia for its aggression.
Here’s why the clash matters.
WATCH BELOW: Russia, Ukraine incident a ‘dangerous escalation’, says Nikki Haley
On Sunday, Nov. 25, three Ukrainian vessels were sailing from the port of Odessa, located in the Black Sea, to Mariupol, located in the Sea of Azov.
Both Odessa and Mariupol are Ukrainian ports on opposite sides of the Crimean Peninsula.
Sailing from one to the other requires passage through what is known as the Kerch Strait.
WATCH BELOW: Ukraine’s president proposes parliament declare martial law after Russian military attack on navy ships
And while Ukraine says a 2003 treaty between itself and Russia designates the Kerch Strait as shared territorial waters, Russian coast guards blocked passage of the Ukrainian ships through the strait on Sunday before ramming one vessel and seizing all three, including the sailors on board.
Accounts of the number of sailors injured as a result varies: Russia says it only injured three and accused the sailors of “banditry,” while Ukraine says six were hurt when the Russian coast guard opened fire and warned the sailors they would “shoot to kill.”
Shortly after, the United Nations’ Security Council agreed to a request for an emergency meeting and the Ukrainian representative asked for a fresh round of sanctions to be applied to Russia by member countries.
Why does the confrontation matter?
In short, the clash marks the most significant conflict at sea between Ukraine and Russia since the 2014 annexation of Crimea.
Even though the conflict has been going on for four years, it has played out largely through proxies in the form of Russian-backed separatists fighting Ukrainian forces in Donbass region of eastern Ukraine.
The Ukrainian ships seized by Russia, however, were navy vessels.
WATCH BELOW: Russia blocks Ukrainian navy from entering Sea of Azov
That makes the incident a direct confrontation between vessels operating on behalf of each respective government.
As well, Russia’s actions come within a broader international pattern of interference and aggression against the West, including a continued habit of probing territorial boundaries to test reaction from foreign states.
WATCH BELOW: Trudeau’s thumbs up to Putin
That behaviour comes after it was allowed to annex Crimea and keep the territory with only sanctions as a result.
At the emergency Security Council meeting held Monday, Russia tried to bill the incident as a “violation of the borders of the Russian Federation,” a move quickly shut down in a vote by member states including the U.S., U.K., France and Germany.
Jonathan Allen, the U.K.’s deputy permanent representative to the UN, described the move as Russia having “deliberately chose a provocative title for their meeting” and added they wanted to “play victim” because they recognized their position was weak.
“We have seen this game before,” Allen added.
“Russia seems to hope the international community will simply acquiesce and accept this as a new reality. We will not.”
The Russian meeting request was voted down and the Ukrainian request adopted instead.
What is Canada doing?
Canada was not present at the emergency meeting, given it does not hold one of the rotating seats on the Security Council.
So far though, there’s no word on whether the government is considering applying further sanctions against Russia for its actions.
Foreign Affairs Minister Chrystia Freeland issued a tweet on Sunday, condemning Russia and calling for the Ukrainian vessels to be released immediately.
Following the Security Council meeting, Freeland issued a more fulsome statement to reporters.
“Canada strongly condemns Russia’s actions against Ukraine in the Sea of Azov and Kerch Strait,” Freeland said.
“We call on Russia to immediately de-escalate, release the captured crew and vessels and not impede passage through the Kerch Strait.”
WATCH BELOW: Chrystia Freeland tells reporters she has raised Russian ship seizure with allies
Freeland also added that she spoke on Sunday with her Ukrainian counterpart as well as other Western allies.
“Yesterday, I spoke with Pavlo Klimkin, Ukraine’s Foreign Minister, and assured him of Canada’s unwavering support for Ukraine’s sovereignty. Canada is also in contact with its G7 and NATO allies on this matter,” she continued.
“The Government of Canada is unequivocal in its support for Ukraine and in its condemnation of Russia’s illegal invasion and annexation of Crimea. Canada will always be a steadfast partner of the people of Ukraine, and we will continue to work with our allies to hold Russia to account for its unacceptable behaviour.”
WATCH BELOW: Controversial bridge links Russia to annexed Crimea
The Canadian Forces also said it was monitoring the situation, given the presence of Canadian troops on Operation Unifier and Operation Reassurance.
Roughly 200 Canadian military trainers rotate through Operation Unifier to help train Ukrainian soldiers, and are scheduled to remain there until March 2019.
Another 835 Canadian sailors, soldiers and members of the air force are deployed to Central and Eastern Europe for Operation Reassurance, which is part of an ongoing NATO effort to deter Russian aggression in the region.
That mission will continue until March 2023.
He also said the military would not comment on whether it would change any rules of engagement, force protection measures or specifics about tactics and techniques for operational security reasons, and that the same message applied to Operation Reassurance.