The United States has begun flying piloted surveillance missions over Nigeria as part of the search efforts for the nearly 300 schoolgirls kidnapped last month. It is unclear how many planes are involved, but the State Department says it is providing “intelligence, surveillance and reconnaissance support” to the Nigerian government. On Monday, a Nigerian official said the government is exploring “all options” to rescue the girls from captivity.

Mike Omeri: “All options are open. At the moment, because all options are open, we are interacting with experts, military and intelligence experts from other parts of the world. So these are a part of the options that are available to us and many more. If it is necessary that we use whatever kind of action to get our girls out of the captivity that they are in now, we will do it.”

The Nigerian government has already rejected a Boko Haram proposal to free the girls in return for the release of the militant group’s prisoners. Boko Haram leader Abubakar Shekau floated the offer in a video on Monday.

Abubakar Shekau: “By Allah, these girls will not leave our hands until you release our brothers in your prison. You took our brothers four or five years ago, and now they are in your prisons. You do many things, and now you talk of these girls. We will not let them go until you release our brothers. We will not let them go until you release our brothers.”

The Boko Haram’s video showed close to half of the nearly 300 missing girls. It was the first public image of the kidnapped schoolgirls since their abduction nearly one month ago.

Pro-Russian groups in eastern Ukraine have asked to join Russia following this weekend’s chaotic referendum for self-rule. On Monday, rebel leaders declared an autonomous “People’s Republic of Donetsk” and called for Russian annexation like that in Crimea earlier this year. The Ukrainian government in Kiev has refused to recognize the separatists’ bid. Russia has also stopped short of an endorsement and is unlikely to carry out another annexation.

New studies show global warming has helped cause an irreversible collapse of the ice sheet in western Antarctica. Scientists from NASA and the University of Washington say human driven-climate change has sped up the glaciers’ retreat, threatening a global sea rise in the coming centuries from four to 13 feet. In a video released by NASA, scientist Eric Rignot of the University of California-Irvine said the melting has “passed the point of no return.”

Eric Rignot: “We’ve passed the point of no return, and at this point it’s just a matter of time before these glaciers completely disappear to sea. This system is evolving very fast and is progressing exactly as you would expect if it was about to collapse to sea. They’re retreating at rates of about a kilometer per year. If these glaciers were sustaining this rate of retreat, they would disappear completely in a couple of centuries.”

Rising sea levels pose the biggest threat to coastal areas and low-lying island nations, which are vulnerable to surging waters like those seen in Superstorm Sandy.

A bipartisan measure to encourage energy efficiency has failed in the Senate following Republican obstruction. The noncontroversial bill called for new efficiency standards in federal and private buildings. But it crumbled on Monday after Republicans tried to add approval of the Keystone XL oil pipeline and the blocking of new U.S. Environmental Protection Agency regulations. Senate Majority Leader Harry Reid refused to grant a vote on the amendments, leading Republicans to filibuster the overall bill.

More than 150 same-sex couples have exchanged vows in Arkansas following a court ruling striking down the state’s marriage equality ban. On Monday, a long procession of couples tied the knot at the county courthouse in Little Rock.

Unidentified 1: “Words cannot really explain the feeling that we have. I mean, there is so much love in that room right now, and the amount of energy that is being projected by everybody.”

Unidentified 2: “We had a ceremony about seven years ago in our home, but it wasn’t recognized, of course, by the state. So this is a huge deal.”

Unidentified 3: “I figured we’d be the last state, you know? I mean, I didn’t even think we’d have a lottery. Sure enough, I’d be standing here talking to you today with my family, fixing to do one of the greatest things in the world and get to be with my wife. Now she’s going to be recognized as my wife.”

The Arkansas ban was struck down on Friday, making Arkansas the sixth state to have its gay marriage ban overturned this year. The Arkansas attorney general has appealed, but the state Supreme Court put off ruling on whether to halt the marriages until today.

Texas is set to carry out the first U.S. execution since last month’s botched killing of a death row prisoner in Oklahoma. Robert James Campbell, a convicted rapist and murderer, is scheduled for death Tuesday evening. As in the Oklahoma case, Texas officials have refused to reveal the source of the sedative that will be used in the lethal injection. Campbell’s attorneys have asked for a stay and the lifting of the secrecy surrounding the execution drug. They have also accused state officials of hiding evidence that Campbell has an intellectual disability, known more commonly as mental retardation. Campbell has an IQ of 69, which falls under the standard score of 70 used to diagnose intellectual disabilities.

The Obama administration has offered the Senate expanded access to secret memos authorizing the killings of Americans overseas in a bid to defuse opposition to a judicial nominee that helped author them. A number of senators have voiced opposition to the nomination of David Barron to the U.S. Court of Appeals for the 1st Circuit. While serving in the Justice Department’s Office of Legal Counsel, Barron helped write at least two memos that underpinned the government’s killing of the American-born cleric Anwar al-Awlaki. But senators including Mark Udall of Colorado and Rand Paul of Kentucky have said they will remain opposed to Barron’s nomination unless the memos are released to the public.

Several New York City Council members are calling for leniency in the sentencing of Occupy Wall Street activist Cecily McMillan following her conviction of assaulting a police officer. McMillan says she struck out instinctively when her breast was grabbed from behind. She faces up to seven years in prison at her sentencing next week. On Monday, Council Member Laurie Cumbo was among five council members to voice support for McMillan. She was joined by Yetta Kurland of the National Lawyers Guild.

Laurie Cumbo: “This a time where we have to make sure that our women are treated with dignity, with respect. We have to make sure that all law enforcement respect women, respect all individuals. But we can’t any longer continue to have our women attacked in ways that are dangerous, that are harmful, that are unconstitutional.”

Yetta Kurland: “Recently, somebody died in Rikers because of the conditions. We’re not able to talk directly with Cecily right now, but our thoughts are with her. And you saw a large group of people coming out today to give support and to ask the judge for leniency in the sentencing that’s upcoming.”

McMillan will be sentenced on Monday. Nine of the 12 jurors who convicted her have written to the judge asking for leniency.

The head of the International Monetary Fund has canceled a commencement speech at Smith College after students and faculty voiced protest. Nearly 500 people signed a petition opposing the appearance of Christine Lagarde, calling the IMF “a primary culprit in the failed developmental policies implanted in some of the world’s poorest countries … strengthening imperialist and patriarchal systems that oppress and abuse women worldwide.” Following the petition, Lagarde said she is withdrawing to “preserve the celebratory spirit of commencement day.” The move comes one week after Secretary of State Condoleezza Rice cancelled a commencement address at Rutgers University following a wave of campus protest.

A candidate in North Carolina’s Democratic primary has died in a fall at his home. Keith Crisco had trailed former American Idol contestant Clay Aiken in last week’s contest and was apparently preparing to concede. Aiken paid tribute to Crisco by suspending his campaign and turning his website all black. He will square off in November against Republican incumbent Renee Ellmers.