Russia fired at and captured three Ukrainian boats in the sea off Crimea on Sunday, sparking a major escalation of tensions between the neighboring countries.

The news revived memories of Russia’s 2014 annexation of Crimea, the Black Sea peninsula previously controlled by Ukraine, and raised further concerns over Russia’s territorial ambitions.

At the center of the dispute is the strategically important Sea of Azov, a body of water bordered by Ukraine, Crimea and Russia and connected to the Black Sea by a strait to the south.

Here’s what to know about the situation.

What led to this?
In 2014, Ukraine erupted in a revolution that pitted pro-Russian and pro-E.U. segments of its population against one another, reflecting internal disputes over whether Ukraine should be closer with the nuclear superpower to its east or the democratic union to its west.

Not long after, Russian soldiers crossed the border into Crimea, the peninsula in the Black Sea that became part of Ukraine after the ..

(TIJUANA, Mexico) — Mexico looked set to shore up security near its border with the United States on Monday, and local authorities said that 39 migrants were arrested after a peaceful march devolved into mayhem when U.S. agents fired tear gas into Mexico to stop some migrants who tried to breach the international line.

Mexico’s Interior Ministry said it would immediately deport those who tried to “violently” enter the U.S. from Tijuana. Meanwhile, Tijuana’s municipal government said that more than three-dozen migrants were arrested for disturbing the peace and other charges stemming from the march and what followed.

On Sunday, the situation at the border devolved after a large group marched to the U.S. border to appeal for the U.S. to speed processing of asylum claims for Central American migrants marooned in Tijuana.

There, some attempted to get through the fencing and wire separating the two countries, leading U.S. agents to fire tear gas.

American authorities also shut down the ..

(LONDON) — Prime Minister Theresa May made a blunt appeal to skeptical lawmakers on Monday to back her divorce deal with the European Union: It isn’t perfect, but it’s all there is, and the alternative is a leap into the unknown.

In essence, she urged Parliament: Let’s agree and move on, for the sake of the voters.

Britain and the 27 other EU leaders signed off on a Brexit deal Sunday after more than a year and a half of tough negotiations. It was a day many doubted would ever come, but May was anything but triumphant as she reported back to Parliament, which now controls the fate of the deal. May confirmed that British lawmakers will vote Dec. 11, after several days of debate, on whether to approve or reject the agreement.

Scores of legislators — from both the opposition and May’s governing Conservative Party — have vowed to oppose it. Rejection would plunge Britain into a political crisis and potential financial turmoil just weeks before it is due to leave the EU on March 29.

“No..