Russian troops have seized part of Ukraine’s Crimean Peninsula in what has become Moscow’s biggest confrontation with the West since the Cold War. The troops took action after Russia’s Parliament gave President Vladimir Putin a green light to protect Russian interests following the ouster of Ukraine’s pro-Russian prime minister, Viktor Yanukovych. Earlier today, Russian troops seized a Ukraine Coast Guard base in the Crimean city of Balaklava. On Sunday, the new head of Ukraine’s navy defected to Russia. The United States and other nations say they are suspending preparations for this year’s G8 summit in Sochi, Russia. Speaking on NBC’s Meet the Press, Secretary of State John Kerry said the United States could impose sanctions to condemn Putin’s actions.

John Kerry: “Russia is going to lose. The Russian people are going to lose. He’s going to lose all of the glow that came out of the Olympics, his $60 billion extravaganza. He is not going to have a Sochi G8. He may not even remain in the G8 if this continues. And he may find himself with asset freezes on Russian business. American business may pull back. There may be a further tumble of the ruble. There’s a huge price to pay.”

The crisis has hit Russian markets, with Moscow’s main stock index tumbling 9 percent. We’ll have more on Ukraine after headlines.

Nearly 400 opponents of the Keystone XL oil pipeline were arrested Sunday in front of the White House, marking what could be the largest youth sit-in on the environment in a generation.

Protester: “We’re out here to march to the White House to perform the largest act of civil disobedience for the climate movement ever. Hundreds of young people, probably going to be over 1,000 on the march, all came here from all over the country, 42 states, to show President Obama that Keystone XL is not OK, that it is not in our national interest and that we need to reject that pipeline and keep the tar sands in the ground.”

Students from more than 80 colleges rallied at Georgetown University and then marched to the White House, where some unfurled a black tarp and lay on the sidewalk to create a “human oil spill.” Hundreds locked themselves to the White House fence before being arrested. President Obama is expected to make a decision on whether to approve the Keystone XL pipeline in the coming months. We’ll have more on the protest and the pipeline later in the broadcast.

Venezuelan President Nicolás Maduro is facing a new round of protests against his government. Despite the Carnival of Brazil holiday, thousands of opposition protesters marched and then clashed with police Sunday in the capital Caracas. At least 17 people have died in Venezuela’s worst unrest for a decade.

In Nigeria, more than 100 people are dead after the latest attacks attributed to the Islamist group Boko Haram. Scores were killed by bomb blasts Saturday in the city of Maiduguri, including children who were watching a soccer game. At least 51 more died when gunmen attacked a nearby village.

In China, a group of people armed with knives attacked a crowded railway station in the southwestern city of Kunming on Saturday, killing at least 29 people and wounding 143. The government blamed the attack on Muslim Uyghur separatists, and police have begun rounding up Uyghurs for questioning.

In news from Afghanistan, a radio station owner who airs ads paid for by U.S. forces says those same forces raided his station, beat him and threatened to kill him on Thursday, before releasing him the next day without charge. Qazi Nasir Mudassir told The New York Times that the U.S. special forces, who hooded him and damaged his equipment, appeared to be unaware that his station is largely supported by pro-government ads paid for by the U.S. military — ads which have earned him death threats from the Taliban. U.S. forces said the operation was “Afghan-led,” but Afghan officials said they were unaware of it, and local police said they did not hear about the raid until it was underway.

Afghan President Hamid Karzai has renewed his criticism of the U.S.-led occupation of Afghanistan in an interview with The Washington Post. Karzai said the war was waged to serve U.S. interests and that “Afghans died in a war that’s not ours.” Despite pressure from Obama, Karzai has so far refused to sign a deal to keep U.S. troops in Afghanistan beyond this year.

A former Guantánamo Bay prisoner who spent three years in U.S. custody without charge or trial has been ordered to remain in detention in Britain following his arrest on terrorism charges related to the conflict in Syria. Moazzam Begg appeared in a London court Saturday while hundreds of supporters rallied in his home city of Birmingham. Begg, who heads the prisoner advocacy group Cage, says he has been “harassed” by authorities for investigating British complicity in torture. To see our interviews with Moazzam Begg, you can go to democracynow.org.

In Pakistan, the latest attack on a polio vaccination team killed at least 13 people on Saturday in the country’s northwest. The provincial governor condemned the killings.

Shaukatullah Khan, governor of KPK province: “These martyrs had not come here to attack anybody’s house or to carry out any such activity. They had come here to administer life-saving drops to our children, to prevent this (polio) disability among our people. But they have been brutally killed, which is not the tradition of this region.”

No one claimed responsibility for the attack, but the Taliban has previously targeted health workers after it was revealed the CIA used a fake vaccination program to help locate Osama bin Laden. Hours after the attack, the Pakistani Taliban announced a month-long ceasefire. Talks between the Taliban and the government had broken down last month.

Osama bin Laden’s son-in-law goes on trial today in New York City. Sulaiman Abu Ghaith is charged with urging the killing of Americans after the September 11 attacks. He is the highest-ranking member of al-Qaeda to stand trial inside the United States following the 9/11 attacks.

A member of the Cuban Five is back in Cuba after more than 15 years in prison in the United States. Fernando González was deported on Friday after his release from prison. He spoke after arriving home.

Fernando González: “The intense emotions I have felt in the last day and a half since setting foot on this dear land are indescribable. Not even the most creative of imaginations could have prepared me for what I have been living since stepping off the stairs of the airplane that brought me to the homeland.”

The Cuban Five were arrested in 1998 and later convicted of conspiracy to commit espionage. They say they were not spying on the United States, but trying to monitor violent right-wing Cuban exile groups. González is the second member to be freed; three others remain in prison. Click here see our interview with René González, the first Cuban Five member freed.

In Florida, an African-American woman sentenced to 20 years in prison for firing what she says was a warning shot into a wall near her abusive husband is now facing triple her original sentence. Alexander’s case generated national outrage and comparisons to George Zimmerman, who was acquitted for shooting Trayvon Martin dead. After a state appeals court ordered a new trial over faulty jury instructions, Florida prosecutors say they will now try to put Alexander behind bars for 60 years at her July trial, which would essentially amount to a life sentence for the 33-year-old mother of three.

Federal regulators have taken a step toward blocking what would be North America’s largest open-pit mine. The Environmental Protection Agency says it is initiating a process to protect Alaska’s Bristol Bay from the potentially “irreversible” impacts of the Pebble gold-and-copper mine. In January, an EPA report found the project could threaten the salmon population and the livelihoods of Alaska Natives.

Idaho Governor C.L. “Butch” Otter has signed a so-called ag-gag law, making Idaho the seventh state to criminalize the act of filming without permission in farming facilities. The ban comes after undercover activists in Idaho filmed workers stomping on cows, beating, dragging and even sexually abusing them at a dairy farm.

The Los Angeles City Council has voted unanimously to advance a ban on oil and gas fracking in the city. The motion passed on Friday instructs the city’s attorney to draft new rules that will impose a moratorium on fracking until environmental protections are in place. Los Angeles would be the first oil-producing city in California to impose a ban on fracking.

The powerful pro-Israel group AIPAC is holding its annual conference in Washington, D.C. Protesters led by CodePink gathered outside the convention hall Sunday to protest Israel’s treatment of Palestinians and call for peace and diplomacy with Iran. This is CodePink’s Medea Benjamin.

Medea Benjamin: “The American people want diplomacy to work. The American people don’t want war. The American people look at Iraq and say, 'Oh, AIPAC was one of those groups that pushed us into that war. How did that work out?'”

President Obama is due to meet with Israeli Prime Minister Benjamin Netanyahu at the White House today.

Israel is facing condemnation over the killing of Palestinians in the Occupied Territories. Over the weekend, Israeli troops shot and killed a Palestinian woman in the Gaza Strip. The military says it fired on a group of people who did not heed calls to retreat from the border. Relatives said the victim, Amna Qdaih, was mentally ill. Last week, Amnesty International accused Israeli forces of killing dozens of civilians in possible war crimes in the West Bank; on the same day, troops shot and killed a man who had barricaded himself in his West Bank home.

In South Africa, Olympic and Paralympic runner Oscar Pistorius has gone on trial for the murder of his girlfriend Reeva Steenkamp that occurred last year on Valentine’s Day. Pistorius pleaded not guilty earlier today at his trial, which is being broadcast on its own TV channel. He says he mistook his girlfriend for an intruder.

The 86th Annual Academy Awards were presented Sunday night in Los Angeles. The feature film, “12 Years a Slave,” about a free black man kidnapped and sold into slavery, won for Best Picture, marking the first time the top honor has gone to a film by a black director, Steve McQueen. Lupita Nyong’o, who plays the enslaved woman Patsy in the film, won Best Supporting Actress, becoming the first Kenyan to win an Oscar.

Lupita Nyong’o: “It doesn’t escape me for one moment that so much joy in my life is thanks to so much pain in someone else’s, and so I want to salute the spirit of Patsy for her guidance, and for Solomon, thank you for telling her story and your own. When I look down at this golden statue, may it remind me and every little child that no matter where you’re from, your dreams are valid. Thank you.”

Matthew McConaughey won Best Actor and Jared Leto won Best Supporting Actor for their roles in Dallas Buyers Club, a film about the difficulty of obtaining medication in the early days of the HIV/AIDS epidemic. “20 Feet from Stardom,” about backup singers, won Best Feature Documentary.