Sen. Bernie Sanders (I-Vt.) was probably being only a little sarcastic Monday night when he thanked libertarian-leaning conservative donors and activists Charles and David Koch for supporting his most famous proposal. "Let me thank the Koch brothers, of all people, for sponsoring a study that shows that Medicare for All would save the American people $2 trillion over a 10-year period," Sanders said, pointing to a new study published by Charles Blahous at the Koch-subsidized Mercatus Center at George Mason University.

In the white paper, Blahous estimates that Sanders' universal, single-payer health-care proposal would raise federal spending on health care by about $32.6 trillion from 2022 to 2031, but other economists noted that, according to the same report, federal health-care spending overall would drop by a little more than $2 trillion in that same period. There are a lot of caveats and untested assumptions in the numbers, but Sanders took the unintentional endorsement and ran with it.

Not that Sanders was 100 percent pleased with the Koch brothers. "The insurance companies, the drug companies, Wall Street, and the Koch brothers are devoting a lot of money to lobbying, campaign contributions, and television ads to defeat this proposal," he said. "But they are on the wrong side of history." Somebody should really write a white paper on that argument. Peter Weber

For nearly three decades, a Houston grandmother has been accidentally repping Panama every Fourth of July.

Dale Cheesman and his sister's fiancé were looking over the World Cup schedule on Monday when they saw the Panamanian flag and realized something: It looked exactly like a red, white, and blue shirt Cheesman's 88-year-old grandmother, Shirley, wears on the Fourth of July, and it dawned on them that her patriotic top would be best suited for Panama's Independence Day. "We died laughing," Cheesman told BuzzFeed News. "We showed the family and they did as well."

Cheesman tweeted about the fashion faux pas, and his grandmother's "over 25 years of treason." Before you start calling her Benedict Shirley, know that she finds the whole thing "hilarious," her grandson said, and is going to keep wearing the shirt "because it's a tradition and now it's just a funnier tradition." Catherine Garcia

Update 5:24 p.m. ET: NBC News reporter Julia Ainsley clarified that Michael Cohen's phone calls were being monitored but not listened to. NBC News had originally reported that Cohen's phone lines had been wiretapped — which would allow federal investigators to hear the content of his calls — but Ainsley said that Cohen's phones were merely being subject to a pen register, which would allow agents to determine with whom Cohen was communicating but not what was being said. Our original story appears below.

President Trump's personal lawyer, Michael Cohen, was reportedly wiretapped by federal investigators in the weeks leading up to the raids on his home and office in early April, two people familiar with the legal proceedings told NBC News. After the raids, Trump's legal team reportedly advised the president against contacting Cohen on the suspicion that the lawyer's phone conversations were being recorded by prosecutors.

Trump, who doesn't exactly have a reputation for following his lawyers' advice, apparently placed a call to Cohen in the days after the raid anyway. Rudy Giuliani, who has since joined Trump's legal team, reportedly had to specifically instruct Trump not to call Cohen again after he learned about the president's call, people familiar with the exchange told NBC.

Cohen is expected to be under federal investigation for possible bank fraud, wire fraud, and campaign finance violations. On Thursday, Trump confirmed that Cohen had paid $130,000 to adult film star Stormy Daniels to keep quiet about her allegations of an affair with Trump, although the president stressed that the payment was from his personal funds, rather than from the campaign's coffers.

In order to have obtained a wiretap on Cohen, investigators would have had to have convincingly demonstrated that there is a possibility of an ongoing crime. "The affidavits are typically highly detailed and carefully vetted by experienced lawyers," said former U.S. Attorney Chuck Rosenberg. "In all cases the wiretap must be approved by a federal judge."

At least one phone call between a line linked to Cohen and the White House was reportedly intercepted. Read more about the phone tap at NBC News. Jeva Lange

Mike Pompeo, the CIA director tapped by President Trump to be the next secretary of state, revealed Thursday that scores of Russians were recently killed by U.S. forces in Syria.

Pompeo made the remark while appearing before the Senate Foreign Relations Committee for a confirmation hearing, as he seeks to succeed Rex Tillerson as head of the State Department. The statement, reported by CNN's Jim Sciutto, revealed something that no U.S. officials have publicly confirmed before: that a U.S.-led coalition killed Russian fighters in a February battle in eastern Syria. The U.S. and Russia are involved in a proxy war in Syria, where government forces aligned with Syrian President Bashar al-Assad are battling various rebel groups, but neither country wants to escalate the fighting into a direct conflict between Moscow and Washington.

Russia confirmed in February that "several dozen" Russians were killed or wounded in Syria. At least some of those killed were reportedly mercenaries, paid soldiers fighting for the Kremlin-backed Syrian government.

The U.S. kept fairly quiet about the clash, though one anonymous official told Bloomberg that U.S. forces were responsible for the Russian deaths. Still, Pompeo's explanation to lawmakers that "a couple hundred Russians were killed" at Thursday's public hearing was the first time a U.S. official confirmed the reports.

Moscow denies sending soldiers to fight in Syria, calling them "volunteers," and the U.S. has taken pains to avoid addressing direct conflict with Russia in Syria, lest the proxy war escalate. An American military spokesman told The New York Times that the U.S. would not create conflict with Russian forces and said that only Syrian troops were targeted. Summer Meza

Personal information from up to 87 million Facebook users was improperly shared with data firm Cambridge Analytica, Facebook revealed Wednesday — significantly more than the company's previous estimate of 50 million.

Most of the 87 million users were Americans, the social media company explained in a blog post. Facebook will start notifying users next week if their information was improperly obtained. The post also outlined a number of measures intended to restrict data access for third-party apps, such as disabling a feature that allows users to search for friends using phone numbers, which put "most people on Facebook" at risk of data-scraping.

Facebook has been under intense scrutiny since reports found that Cambridge Analytica, a political consulting firm with ties to President Trump, had harvested user information without permission. Mark Zuckerberg, Facebook's CEO, has agreed to testify before the House Oversight Committee to address the "breach of trust." Summer Meza

Three students were injured when a math teacher fired a semiautomatic handgun at the ceiling of a classroom during a firearm safety course on Tuesday at Seaside High School in Monterey County, California, NBC News reports. "It's the craziest thing," said Fermin Gonzales, whose 17-year-old son was apparently bruised by a bullet fragment. "It could have been very bad."

The math teacher, Dennis Alexander, teaches an administration of justice course, which is where he fired the weapon. He is also a reserve police officer for the Sand City Police Department, although since the incident he has been placed on administrative leave by both the school and the police department. School district officials told local reporters that Alexander had not been authorized to carry a firearm on the school grounds.

The incident occurred a day before nationwide walkouts by students in protest of gun violence. President Trump has pushed for arming teachers as a solution to mass shootings: "History shows that a school shooting lasts, on average, 3 minutes," he tweeted last month. "It takes police & first responders approximately 5 to 8 minutes to get to site of crime. Highly trained, gun adept, teachers/coaches would solve the problem instantly, before police arrive." Jeva Lange

You know that phrase you start to hear all the time on TV in the fall, something like "I'm Angus and I approve this message" or "This ad was paid for by Canines for a Better America?" The Federal Election Commission clarified in an opinion in December that such a disclaimer needs to be visible on ads on websites like Facebook too — only it doesn't seem like anyone is actually obeying. A ProPublica investigation found that of 300 political ads that have run on Facebook, fewer than 40 actually met the FEC's disclaimer laws.

Ads lacking the proper FEC language include ones paid for by the Democratic National Committee and President Trump's 2020 campaign. Fines for "knowing and willful" violations of the law can be over $1,000.

The regulations are under particular scrutiny now, as it has become increasingly clear that Russian agents used Facebook to promote their agenda during the 2016 election. "Foreign contributions to campaigns for U.S. federal office are illegal," ProPublica notes. "Online, advertisers can target ads to relatively small groups of people. Once the marketing campaign is over, the ads disappear. This makes it difficult for the public to scrutinize them."

The FEC's rules have changed as the nature of online advertising has, too. In 2011, when ads on Facebook were limited to small thumbnails and short text, the FEC agreed that the disclaimer could appear after clicking through the ad. "The functionality and capabilities of today's Facebook Video and Image ads can accommodate the information without the same constrictions imposed by the character-limited ads that Facebook presented to the Commission in 2011," the commission wrote in December.

Read more about the law, and who is and is not complying with it, at ProPublica. Jeva Lange