Secretary of State John Kerry on Sunday warned Russia against its military incursion into Ukraine, saying the United States could respond with visa bans, trade penalties, and a boycott of the next G8 summit to be held in Sochi, Russia, in June if Russia does not withdraw its forces. On Face the Nation, Kerry called Russia's deployment of troops to Crimea an "incredible act of aggression," adding that Russian President Vladimir Putin had acted out of "weakness and out of a certain kind of desperation."

"It is really a stunning, willful choice by President Putin to invade another country," Kerry said. "You just don't in the 21st century behave in 19th century fashion by invading another country on completely trumped up pretext."

The U.S., France, Britain, and Canada have already announced they will sit out upcoming preparatory talks ahead of the G8 summit. Jon Terbush

An explosion at an Ariana Grande concert in Manchester, England, killed at least 19 people and wounded 50 while Monday's Late Late Show was taping, and host James Corden sat down after the audience left to offer his condolences and thoughts. "It shocks me every time we hear this sort of news, that attacks like this can happen, but especially when there will be so many children at this concert tonight," he said.

Most of his U.S. viewers won't have been to Manchester, he said, but they will know something about it: Its famous soccer teams, its musical history as the birthplace of both Oasis and Joy Division, among other bands. "But when I think of Manchester, the place that I know, I think of the spirit of the people there, and I'm telling you a more tight-knit group of people you will be hard-pressed to find," Corden said. "Strong, proud, caring people, with community as its core. And if it was even possible, the spirit of the people of Manchester will grow even stronger this evening." You can watch his monologue below. Peter Weber

On Sunday in Saudi Arabia, King Salman led President Trump on a tour of the new Global Center for Combating Extremist Ideology, and the ceremony included some odd moments. Yeah, "this is, without question, the strangest thing I've ever seen a president do," Jimmy Kimmel said on Monday's Kimmel Live, playing some footage of Trump, Salman, and Egypt's president touching a glowing white orb. He made an Access Hollywood joke, then said the orb-fondling appears to be "their version of a ribbon-cutting ceremony over there? But I have to say, the president seemed kind of different after he touched it." Kimmel cut to Trump, doctored in a disturbing way, speaking, and ended with an explanation for that sinkhole opening up in front of Mar-a-Lago. Watch below. Peter Weber

Several al Qaeda in the Arabian Peninsula militants were killed early Tuesday morning as U.S. military forces conducted a ground raid in central Yemen's Marib Governorate.

Colonel John Thomas, a spokesman for U.S. Central Command, said the raid at a known AQAP compound began as a mission to gather information on the group, but when U.S. forces were met with resistance, they responded with gunfire and precision air strikes, ABC News reports. Seven AQAP militants were killed, but there are no reports of any civilian or U.S. military casualties.

Thomas said the mission, the first ground operation conducted by the U.S. military in Marib province, was done "in full coordination with Arab partners in the area." Catherine Garcia

The Golden State Warriors are heading to their third straight NBA Finals, after completing a four-game sweep of the San Antonio Spurs with a 129-115 win in San Antonio on Monday night. The Warriors, who haven't lost a playoff game since Game 7 of last year's finals against the Cleveland Cavaliers, are the first team in NBA history to start the playoffs with a 12-0 record. Stephen Curry scored 36 points for the Warriors, while Kyle Anderson led the injury-plagued Spurs with 20 points; Spurs great Manu Ginobili, who notched 15 points in what is likely his final NBA game, got a standing ovation when he walked off court in the fourth quarter.

The Cavs are facing the Boston Celtics in Game 4 on Tuesday, with a 2-1 series lead, and if they prevail, the Warriors and Cavs would be the first teams to face each other for three consecutive Finals. Peter Weber

One witness who fled the Manchester Arena after a suspected terrorist attack Monday night during an Ariana Grande concert described a chaotic scene "like something out of a war film."

Speaking to BBC 5 Live, a man named Andy said he was waiting for his wife and daughter in the arena's foyer when an explosion knocked him to the ground. "When I get up and look round, there's just bodies everywhere," he said. "I reckon 20 to 30 bodies. I can't say if some of them were dead, but they looked dead. They were covered in blood and were really seriously hurt." Andy also said he saw "kids and teenagers just lying there screaming."

A woman named Anne-Marie told BBC 5 Live she was at the concert with her 13-year-old daughter, and after she felt the building shudder, everyone "went into absolute panic." Fearing there was a gunman, "people were dropping to the floor," Anne-Marie said, and because there "were a hell of a lot of children in the building unaccompanied," she tried to "offer my support to a number of girls who were there on their own who were hysterical. They were around my daughter's age if not younger." Another mother at the concert, Rachel, told BBC Radio Manchester that she left a few minutes early with her 14-year-old daughter to avoid the crowds exiting at the end of the concert, and they heard an "almighty bang." They turned a corner, and "there was a horrific stampede of people coming down the steps, people falling on the floor. I grabbed my daughter and we just ran. There were people being crushed on the floor." Catherine Garcia

Chief Constable Ian Hopkins with the Greater Manchester Police gave an update early Tuesday morning about the explosion at the Manchester Arena Monday night at the conclusion of an Ariana Grande concert, confirming that 19 people died and 50 were injured.

The victims have been taken to six hospitals in the Manchester area, Hopkins said, and police are "treating this as a terrorist incident until we have more information." It's a "very concerning time for everyone," he added. "We are doing all that we can, working with local and national agencies, to support those affected as we gather information on what happened last night." He called on anyone with information to notify police, and urged the residents of Manchester to "remain vigilant." Catherine Garcia

British Prime Minister Theresa May has responded to the explosion at the Manchester Arena late Monday night, saying the government is "working to establish the full details of what is being treated by the police as an appalling terrorist attack."

May added that "all our thoughts are with the victims and the families of those who have been affected." Labour Party leader Jeremy Corbyn called the incident "terrible," and said his thoughts are with "all those affected and our brilliant emergency services," while Liberal Democrats leader Tim Farron sent his "deepest condolences to the victims and families in Manchester. As always, our emergency services have shown great bravery and strength." The Guardian reports that in the wake of the explosion, which left at least 19 people dead and 50 injured, campaigning for June's general election has been suspended. Catherine Garcia