Bernie Sanders has finally crossed the line. With his chances of winning the Democratic presidential nomination fading fast, he’s ramping up the radical rhetoric and dropping the pretense of political acceptability crafted during his 25 years in Congress. The junior senator from Vermont has tried during the campaign to convince Americans that his extreme views are merely a Yankee variant of those commonly found in all the best European social democracies. Now he’s showing who he really is: a far-left revolutionary who despises the bourgeois values of liberty and self-determination that most Americans hold dear.

More than that, though, Sanders supports those who take up arms against the United States government. At a boisterous town hall meeting Monday in San Juan, Puerto Rico, Sanders demanded that President Obama release Oscar López Rivera from federal prison in Terre Haute, Indiana. The 73-year-old mastermind of the Fuerzas Armadas de Liberación Nacional (FALN), a militant Puerto Rican nationalist organization that terrorized Chicago and New York during the 1970s, López Rivera has served 34 years of a 55-year sentence for seditious conspiracy against the United States and other charges. In 1988, he was sentenced to an additional 12 years for his role in an escape plot involving plans to murder prison guards. “Oscar López Rivera is one of the longest-serving political prisoners in history—34 years, longer than Nelson Mandela,” said Sanders at a rally. “We are talking about a Vietnam War veteran who was awarded a Bronze Star. I say to President Obama—let him out!” Sanders repeated his demands on Twitter: “Oscar López Rivera has served 34 years in prison for his commitment to Puerto Rico’s independence. I say to President Obama: let him out.”

López Rivera’s supporters like to pretend that he is a political prisoner. He is nothing of the kind. Though his service in Vietnam may have been valiant, upon his return, he took up arms against the United States to achieve the political goal of an independent, Communist Puerto Rico. FALN’s most notorious operation occurred on January 24, 1975, when it planted a ten-pound dynamite bomb that killed four and injured 50 during a busy lunch hour at historic Fraunces Tavern in Lower Manhattan. But Fraunces Tavern is only the best-known of the FALN’s murderous plots. As Bryan Burrough reports in his excellent history of 1970s radicalism, Days of Rage, the FALN enjoyed a formal alliance with the era’s most notorious left-wing terrorists—the renegade Weather Underground movement led by Bill Ayers and Bernardine Dohrn. In December 1974, an NYPD rookie lost an eye when a FALN bomb exploded in East Harlem. On October 27, 1975, FALN planted a bomb at the State Department in Washington.

On August 3, 1977, several Manhattan office buildings were rocked by FALN bombs. The force of the device that exploded at the Mobil Building at 150 East 42nd Street blew out the ground-floor windows, showering passersby with glass and critically injuring several people. Twenty-six-year-old Charles Steinberg, recently married and working as a manager at a small employment agency with offices in the building, was blown to bits at his desk. A cop told a reporter from the Daily News that the only way he could describe the bloody scene was as a “human mess.”

The FALN took responsibility for these atrocities and warned of bombs placed at 13 other buildings, including the World Trade Center. The NYPD and FDNY evacuated as many as 100,000 people from potential targets throughout the city. Mayor Abe Beame called the attack—and the barrage of threats that followed—an “outrageous act of terrorism.” With the NYPD already dealing with a manhunt for the Son of Sam killer and the aftermath of blackouts that had plagued the city earlier that summer, Beame ordered the rehiring of more than 100 recently laid-off cops to go after the FALN bombers. In an editorial, the New York Times declared that “for those who have lived through this mad week in New York there is a shared sense of outrage and impotence.”

While some say that Oscar López Rivera is innocent of the charges against him, more commonly, his supporters concede his guilt but argue that he should be freed because, like Nelson Mandela, his cause was just. What an insult to the memory of Mandela. No one disputes that the FALN killed innocent people or that Oscar López Rivera was one of its leaders. True, there is no evidence that López Rivera killed anyone with his own hands, but you could have said the same of Osama bin Laden. Plenty of evidence exists that López Rivera urged others to murder and maim in the cause of Puerto Rican nationalism, and that he organized and participated in terrorist plots.

Moreover, before leaving office, President Bill Clinton, looking to win the support New York’s Puerto Rican community for his wife’s looming senatorial campaign, offered López Rivera a conditional clemency. The condition? That López Rivera renounce terrorism and armed struggle against the United States. Twelve of his jailed FALN confederates accepted the offer. López Rivera rejected it. “The whole thing of contrition, atonement, I have problems with that,” he told a reporter.

That so many on the American left are convinced that this unabashed enemy of the United States has been railroaded and should be released from prison and allowed to resume his violent pursuit of Puerto Rican independence—which, by the way, just 5 percent of Puerto Ricans support—points to a disturbing question: What does someone have to do or say to be considered a traitor anymore? That Bernie Sanders himself thinks this unrepentant terrorist should be allowed to walk free is more than disqualifying—it’s insane.

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