World News at a Glance

Migrants Rush U.S. Border in Tijuana, but Fall Back in Face of Tear Gas

A peaceful march by Central American migrants waiting at the southwestern U.S. border veered out of control Sunday afternoon, as hundreds of people tried to evade a Mexican police blockade and run toward a giant border crossing that leads into San Diego. In response, the U.S. Customs and Border Protection agency shut down the border crossing in both directions and fired tear gas to push back migrants from the border fence. Some of the migrants told The New York Times they thought they could negotiate with U.S. officials, but as they approached the fence, they were met with several rounds of tear gas.

Marching to End Violence Against Women

Thousands of people took to the streets of countries around the globe Sunday, a day set aside by the United Nations to raise awareness of and to protest violence against women. It was the beginning of a 16-day campaign urging individuals and organizations to fight the kind of violence that will affect more than a third of women globally during their lives, according to the United Nations. Michelle Bachelet, the former president of Chile and the U.N.'s high commissioner for human rights, said on Twitter: “I support the millions of women around the world who have dared to speak out against violence and harassment.”

U.K. and EU Leaders Clinch Brexit Divorce Terms

More than four decades after Britain tied itself to its Continental neighbors, Prime Minister Theresa May obtained the approval Sunday of the other 27 European Union members on a formal divorce pact from the bloc, a consequential step intended to take the country on a new, if unclear, path. The journey has been long and tortuous for both sides, and the drama is hardly over. May must still get approval for the deal — a dense, legally binding divorce settlement and a set of political promises for Britain’s future relationship with the bloc — from an outspokenly unhappy British Parliament.

Syria Urges U.N. to Condemn Rebels After Apparent Chemical Attack

Syria called on the United Nations on Sunday to condemn its rebel foes after an apparent attack with unidentified chemicals in Aleppo sent scores of choking victims to hospitals. Medics reported a flood of patients with breathing troubles, inflamed eyes and other symptoms after a shelling attack Saturday that Syrian and Russian officials blamed on the rebels. The Syrian state news service, SANA, said that more than 100 people had been affected, although it reported no deaths. The Syrian Observatory for Human Rights released slightly lower numbers. A spokesman for Russia’s Ministry of Defense said 46 people, including eight children, had been exposed.

Afghanistan Considers Delaying Presidential Election

Election officials in Afghanistan are considering delaying next year’s presidential election by several months, amid disarray in counting votes from last month’s parliamentary balloting. Holding presidential elections by April 20 was previously one of international donors’ red lines in Afghanistan, especially after an embarrassing, four-year delay in holding parliamentary elections. Now, however, some politicians and observers are suggesting that the electoral fiasco might help encourage peace talks with the Taliban, who are unlikely to agree to a peace deal if a new president is about to be elected for a five-year term.

Ukraine, After Naval Clash With Russia, Considers Martial Law

A dispute between Ukraine and Russia in which each accuses the other of violating laws of the sea escalated sharply Sunday when the Ukrainian navy said the Russian military opened fire on several of its ships, wounding six sailors and seizing the vessels. The incident in and around the Kerch Strait, a narrow body of water separating the Black and Azov seas, marked a pivot in the undeclared war, now nearly 5 years old, between the former members of the Soviet Union. At a midnight meeting, Ukraine’s National Security and Defense Council said it would ask Parliament to declare a state of martial law.