A United Nations envoy and an ITV News journalist were stopped by a group of armed men in Crimea, according to tweets from the reporter. James Mates tweeted that he and UN representative Robert Serry were threatened in a Simferopol coffee shop by pro-Russian men who asked Serry to enter a vehicle. He refused and left in a different waiting car. Serry headed to the airport where he agreed to leave the region if it eases the tension in Crimea.

UN Deputy Secretary General Jan Eliasson released a statement saying the "action should be seriously condemned." ITV News is continuously updating its blog with the latest. --Jordan Valinsky

Hillary Clinton spoke at Yale's Class Day on Sunday, referencing the university's tradition of wearing silly (typically DIY) hats for the occasion by bringing a Ushanka hat along for a predictable joke about President Trump. "A Russian hat," she said, waving but not actually wearing it. "If you can't beat 'em, join 'em."

Clinton also revisited her loss to Trump in a more serious tone. "I'm not over it," she said. "I still think about the 2016 election. I still regret the mistakes I made. I still think, though, that understanding what happened in such a weird and wild election in American history will help us defend our democracy in the future."

Watch the hat moment below. Bonnie Kristian

In a survey of 87 cybersecurity experts published Monday, The Washington Post found they overwhelmingly believe state election systems are vulnerable to hacking in the 2018 midterms.

(The Washington Post)

"We are going to need more money and more guidance on how to effectively defend against the sophisticated adversaries we are facing to get our risk down to acceptable levels," Rep. Jim Langevin (D-R.I.), co-chair of the Congressional Cybersecurity Caucus and one of the experts polled, told the Post. "I hope Congress continues to work to address this vital national security issue," Langevin added. He argues the $380 million allotted for election cybersecurity in March is not enough.

On a more positive note, the experts who spoke with the Post generally agreed systems are more secure than they were in the last election, and there is "no evidence that Russian hackers actually changed any votes in 2016," though they did access some voter data. Bonnie Kristian

The Supreme Court voted 5-4 along ideological lines on Monday to rule that federal arbitration law allows employers to prevent their employees from banding together in class-action lawsuits and require them to go through individual arbitrators for disputes. The ruling, with Justice Neil Gorsuch writing the majority, is a "big win for businesses" and "a major blow to workers," New York's Cristian Farias tweeted.

While supporters of arbitration argue it is cheaper, "critics say companies are trying to strip individuals of important rights, including the ability to band together on claims that as a practical matter are too small to press individually," Bloomberg writes, adding that "about 25 million employees have signed arbitration accords that bar group claims."

Liberal Justice Ruth Bader Ginsburg wrote the 30-page dissent, which is five pages longer than the majority decision, SCOTUSblog reports. She called the ruling "egregiously wrong" and said the Federal Arbitration Act "demands no such suppression for the right of workers to take concerted action for their 'mutual aid or protection.'"

Gorsuch said that the "policy may be debatable but the law is clear: Congress has instructed that arbitration agreements like those before us must be enforced as written." Read more about the decision on Epic Systems Corp. v. Lewis at SCOTUSblog. Jeva Lange

Facebook announced a crackdown on political advertising in early April, a move intended to assuage fears about political misinformation and election meddling. Among the changes, which will be fully implemented Tuesday, Facebook will display who pays for political ads. The social network will also institute a complex process to verify purchasers of U.S. political advertising are Americans (or permanent residents) living in America.

CNN's Donie O'Sullivan decided to experience that process for himself, sharing the results on Twitter. The steps include: giving Facebook your address so the company can physically mail you a verification code, uploading images of your driver's license or passport, and submitting your Social Security number.

Basically, buying a political Facebook ad now requires the same level of personal information as opening a bank account.

And the scope of application for this process is broad. Facebook says it applies to "national issues of public importance" including civil rights, government reform, the exceedingly vague "values," and much more. A number of prominent media organizations, including The Wall Street Journal, The New York Times, and The Washington Post, have sent a letter to Facebook complaining that news content will be inappropriately lumped in with advocacy. Bonnie Kristian

Secretary of State Mike Pompeo threatened Iran with a string of new demands in a Monday speech, following President Trump's recent decision to withdraw the U.S. from the Iran nuclear deal.

To deter Iran from developing nuclear weapons, Pompeo said, the U.S. will impose "the strongest sanctions in history" and create military pressure. "We will track down Iranian operatives and their Hezbollah proxies operating around the world and crush them," said Pompeo. Bloomberg reports that the secretary of state listed 12 "basic requirements" that the U.S. would demand before lessening up the "sting of sanctions." Other demands included releasing Americans held captive in Iran, ceasing support for terrorist groups in the Middle East, and withdrawing military forces from Syria.

The U.S. would eventually be willing to lift Iranian sanctions in exchange for a major change in behavior, America's top diplomat added. If Tehran verifiably ended its nuclear weapons program and stopped its "destabilizing activities in the region," said Pompeo, the U.S. would consider offering "relief." Read more at Bloomberg. Summer Meza

It has been two years since Vermont Sen. Bernie Sanders (I) shook up the Democratic Party with his grassroots movement, but there is growing concern that his "revolution" no longer has the legs to impart real political change, Politico reports in a dissection of Our Revolution.

While the organization does not have formal ties to Sanders, the senator's supporters and operatives formed Our Revolution after he lost the primary to Hillary Clinton as a way to keep up the momentum of the progressive movement. Yet with a leadership crisis — some say the president, Nina Turner, is using the group as a vehicle to get her own exposure ahead of a 2020 presidential run — and a shaky record of transparency and successful endorsements, some believe that Our Revolution is so weak that it could even hurt Sanders by mere association.

Sanders did personally have a significant win recently in Pennsylvania, where he endorsed Braddock Mayor John Fetterman in the lieutenant governor's race. Our Revolution, however, did not back Fetterman, nor did it back the progressive Nebraska candidate Kara Eastman, who won her race against centrist Rep. Brad Ashford (D).

Sanders' 2016 campaign manager, Jeff Weaver, defended Our Revolution, telling Politico that the group "is doing a phenomenal job around the country, helping energize the grassroots, and helping to democratize the Democratic Party." Read more of the criticism of the group, and how it could potentially drag Sanders down, at Politico. Jeva Lange

Don't tell President Trump he got rolled by China. On Fox News Sunday, Treasury Secretary Steven Mnuchin said Trump has put his $150 billion in proposed tariffs "on hold" while the U.S. and China implement a new "framework" in which China lowers tariffs on unspecified U.S. goods, buys more U.S. energy and food, and increase cooperation in safeguarding U.S. technology. Trump began his morning tweets with a defense of the preliminary deal:

"On China, barriers and tariffs to come down for first time," he added. Analysts, and many of his own allies, did not agree with Trump's rosy assessment. "Trump administration gets rolled by the Chinese," tweeted Wall Street Journal trade reporter Bob Davis. Fox Business host Lou Dobbs tweeted: "Chinese say 'No Deal' — U.S. must export like a superpower not an agrarian developing nation half our size!" Sen. Marco Rubio (R-Fla.) summed up the objections in one tweet:

China got Trump's team to drop the threatened tariffs and a specific $200 billion commitment for increased imports, and in return it pledged to buy more U.S. energy and food that it was almost certainly going to import anyway to feed its growing middle class. So "China appears to have the upper hand, but this is just the beginning," says Heather Long at The Washington Post. "There's hope on both sides of the aisle (and in many parts of America) that Trump will hold out for more." Peter Weber