President Trump is taking his immigration rhetoric up to eleven.

Trump on Thursday urged Mexico "in the strongest of terms" to stop what he called an "onslaught" of illegal immigration into the United States. About 4,000 Central American migrants are heading toward the U.S. in hopes of crossing the border, NBC News reports, and the State Department wants Mexico to stop this caravan when it reaches the border with Guatemala. Mexico has dispatched about 500 officers to confront the caravan, but has said they will treat these migrants the same as any others, reports The Washington Post.

Now, the president is warning that if Mexico is unable to stop the group of migrants, which he said includes "MANY CRIMINALS," he will "call up the U.S. military and CLOSE OUR SOUTHERN BORDER!" He also suggested this could damage the recently-signed United States-Mexico-Canada Agreement, as this "assault on our country" is "far more important" than trade.

Trump sought to place blame on Democrats, accusing them, without evidence, of wanting open borders and faulting them for "weak laws" on immigration. Based on his tweetstorm and recent USA Today op-ed, in which he claimed Democrats wanted "open-borders socialism," it seems Trump has found a new favorite talking point for the weeks leading up to the midterms. Brendan Morrow

Former Vice President Joe Biden touted his "sensible" immigration proposals and hit President Trump for a re-election strategy he called "morally bankrupt" in an op-ed published Monday.

In the Miami Herald, Biden called on Congress to "make it official" that "DREAMers are Americans," also saying undocumented immigrants in the United States must be "brought out of the shadows through fair treatment, not ugly threats." The U.S asylum system needs to be improved in ways that will "streamline and strengthen it," Biden wrote.

Biden went on to say that it's "imperative" to secure the border by "improving screening procedures at our legal ports of entry and making smart investments in border technology," but not through building a wall, which Biden referred to as a "slogan divorced from reality."

The Democratic presidential frontrunner went after Trump in the op-ed for policies he says are intended to "assault the dignity of the Latin community and scare voters to turn out on Election Day," also saying that the president "invokes racist invective to describe anyone south of the Rio Grande" while describing "horrifying scenes at the border of kids being kept in cages" that "subvert American values and erode our ability to lead on the global stage."

Biden published his op-ed three days before he'll head to Miami for the first Democratic presidential debate; he's set to take the stage on the second night, June 27. Brendan Morrow

Sen. Bernie Sanders (I-Vt.) will propose Monday eliminating all $1.6 trillion of U.S. student debt and making all public universities, community colleges, and trade schools tuition-free. His plan is broader and more expensive than those offered by fellow 2020 Democratic presidential candidates Sen. Elizabeth Warren (D-Mass.) and Julián Castro. Warren's plan, for example, would cost an estimated $640 billion and eliminate up to $50,000 in debt of people earning less than $100,000, effectively wiping out the student loans of 75 percent of borrowers. Sanders proposes to cancel all student debt, including for private colleges and graduate schools..

Sanders says he will pay for it with a tax on stock transactions and bonds. "This is truly a revolutionary proposal," he told The Washington Post. "In a generation hard hit by the Wall Street crash of 2008, it forgives all student debt and ends the absurdity of sentencing an entire generation to a lifetime of debt for the 'crime' of getting a college education." Sanders said his tax on investments would raise $2 trillion over 10 years, though some tax experts call that an optimistic figure.

Critics say the Sanders proposal would primarily help educated Americans, who typically earn more, and more affluent families. Sanders and his supporters say creating programs that help all Americans, regardless of income, makes the programs more politically durable. Peter Weber

South Bend, Indiana, Mayor Pete Buttigieg held a contentious town hall on Sunday to address anger over the June 16 police shooting of a black man, Eric Logan, by a white police officer. Prosecutors investigating the shooting said Logan, 54, approached Sgt. Ryan O'Neill with a knife after O'Neill confronted him for allegedly breaking into cars. But O'Neill's body camera was not on, and many people at the town hall placed the shooting in the broader context of longstanding tensions between South Bend's black community, which makes up about a quarter of the city's population, and its police force, which is now about 5 percent African American.

Buttigieg, who returned to South Bend from campaigning for the 2020 Democratic presidential nomination, said he has asked the Justice Department's civil rights division to investigate the shooting and the local prosecutor for an independent investigator. He took responsibility for failing to reform the police department. "The effort to recruit more minority officers to the department and the effort to introduce body cameras have not succeeded and I accept responsibility for that," Buttigieg said. He was joined onstage by Police Chief Scott Ruszkowski.

Buttigieg, 37, has had a sometimes-fraught relationship with his city's black community since he demoted the city's first black police chief during his first term as mayor. "Get the people that are racist off the streets," one woman in the audience said during Sunday's town hall. "Reorganize your department. You can do that by Friday." Buttigieg suggested the attention on this police shooting of a black man might "help us do some good" and said he's not "running away from it," and neither can America. "This problem has to get solved in my lifetime. I don't know of a person or a city that has solved it," he said. "But I know that if we do not solve it in my lifetime, it will sink America." Peter Weber

"Everest was first summited in 1953 by Sir Edmund Hillary and Tenzing Norgay," John Oliver said on Sunday's Last Week Tonight. "Before then it had been seen as almost an impossible feat," which probably explains why "Everest" has "become everyone's go-to metaphor for a significant challenge," warranted or not. Now however, "climbing Everest has become dangerously popular," he said. That means high death tolls and long lines to the summit, tons of trash, and a "fecal time bomb" as human waste melts and slides downhill.

"So tonight, let's look at what is causing these issues, how Everest's climbing industry operates, and how we can potentially make things safer," Oliver said. The first problem is that there is a narrow window in which people can summit Everest, sometimes just a few days, and starting in the 1990s, commercial expeditions became available, sometimes with six-figure luxury packages. Oliver explained the difference between Sherpas and sherpas, and the very dangerous and integral role sherpas play. "Huge risks are being taken by sherpas to give their client the bragging rights of conquering 'the ultimate mountain,'" he said, noting that Everest isn't actually the hardest mountain to climb.

Everest is still deadly to unprepared or inexperienced climbers, there is essentially no gate-keeping at the Nepal end — Tibet is stricter in granting permission — and some climbing outfits let anyone try to summit, Oliver said, citing one specific example. "Even Sir Edmund Hillary was depressed at what he had seen Mount Everest become," he said. "Some of the people climbing Everest aren't doing it out of a passion for mountaineering, but just because they want to say they climbed Everest," because "a selfie from the summit of Makalu" won't "get Everest levels of Instagram love." But Oliver had a solution, plus a few interludes from sherpa Rick Astley and some NSFW language. Watch below. Peter Weber

An unidentified U.S. service member was found dead near Ajo, Arizona, on Sunday, according to a statement from Peterson Air Force Base in Colorado Springs, Colorado, home of U.S. Northern Command. It is the second such death this month. On June 1, U.S. Army PFC Steven Hodges was found dead near Nogales. Both service members were assigned to the Southwest Border Support Mission, President Trump's deployment of several thousand active-duty troops to the U.S.-Mexico border. Both deaths are under investigation, but foul play isn't suspected in either case.

Hodges had been assigned to "Task Force Red Lion," a mobile surveillance operation, with the 1st "Tomahawk" Battalion, 23rd Infantry Regiment, 1-2 Stryker Brigade Combat Team, part of the 7th Infantry Division at Joint Base Lewis-McChord, Wash. His body was found on federal land, but few other details have been reported. It is also unclear what the unidentified service member was doing when he died. Ajo is the nearest community to Organ Pipe Cactus National Monument, where the Department of Homeland Security plans to build new border fencing.

Other than hanging razor wire through border towns and spending the summer painting border fencing near Calexico, California, to improve its "aesthetic appearance," it's not clear what U.S. troops are doing at the U.S. border. In Arizona, the Tucson Sentinel reports, "the weather has been hot and dry: temperatures in Arizona's west deserts peaked at about 98 degrees on Sunday, with humidity below 10 percent." Peter Weber

Two days after winning the 2016 presidential election, President Trump fired his transition chief, former Gov. Chris Christie (R-N.J.), and his new transition team discarded Christie's copious files and instead outsourced its nominee vetting to the Republican National Committee. Axios obtained RNC vetting files on about 100 people, many of whom joined the Trump administration as Cabinet secretaries and agency heads.

Some of the young RNC staffers who "scrubbed" the public records of potential Trump hires told Axios the rushed process was "a disaster" and "a clown show" focused on making sure a potential nominee for an often unspecified position was at least "not a kid-toucher." Here are some of the "red flags" the vetters highlighted:

1. Kris Kobach: A potential Homeland Security secretary pick, Kobach's file notes that critics said he spoke at "a 'White Nationalist' conference," "tied him to white supremacist groups," and said "Kobach's college thesis praised Apartheid in South Africa." Kobach headed Trump's short-lived voter fraud commission and was most recently considered for an "immigration czar" post.

2. David Petraeus: The former general was being considered for secretary of state or national security adviser, and along with flagging that "Petraeus has indicated that the U.S. should deal with Russia with a stronger hand" and said "Brexit would 'damage Western security,'" his vetting file warns: "Petraeus is opposed to torture."

3. Rudy Giuliani: Giuliani, now Trump's personal lawyer and at the time under consideration for secretary of state, got his own 25-page RNC dossier on his business ties and "foreign entanglements."

4. Rep. Tulsi Gabbard: Gabbard (D-Hawaii), now running for the 2020 Democratic presidential nomination, was vetted for a position in Trump's administration, reportedly Veterans Affairs secretary. Her file notes that she backed Sen. Bernie Sanders (I-Vt.) and "has given Democrats as many headaches" as "blessings."

5. Laura Ingraham: Trump considered the Fox News host as White House press secretary, and among other controversies, the RNC flagged Ingraham's "Nazi salute controversy," her suggestion "that the Clintons were going to kill FBI Director James Comey," and her stated views that "illegal immigrants who attempt to re-enter the country should be 'shot'" and "people should wear diapers instead of sharing bathrooms with transgender people."

Axios had Chris Christie read his own file on-camera for its Sunday evening HBO show.

Read more tidbits, and responses from the White House and various vetted people, at Axios. Peter Weber