It is conceivable that Labour Party leader Jeremy Corbyn could be the next elected British prime minister. In last year’s general election, the hitherto obscure far-left politician unexpectedly wounded Prime Minister Theresa May, leading to a hung parliament and a weakened leader. May’s Conservative Party has become more divided since, and her diluted plans for Brexit—the political issue that continues to dominate British political life—are deeply unpopular.

In theory, Corbyn should have problems of his own. He is embroiled in a long-running anti-Semitism row, with Labour’s initial refusal to adopt the International Holocaust Remembrance Alliance’s definition of anti-Semitism the most recent incident to give it oxygen. However, these controversies have not yet proved disqualifying. Counterintuitively, there has even been a surge in Labour Party membership and an increase in Corbyn’s lead over the Conservatives in some polls.

Yet, for many reasons, Corbyn is uniquely unsuitable to be prime minister. This is someone who accepted money from Iran to present on the government-affiliated channel Press TV and who invited Linda Quigley and Gerry MacLochlainn, both convicted of activity connected to the Irish Republican Army, to Parliament just two weeks after the IRA had killed five people and almost assassinated the British prime minister in the 1984 Brighton bombing.

Then, there is his long-held contempt for NATO and his admiration of far-left revolutionaries such as Fidel Castroand Hugo Chávez (reflected in the advisors and political allies closest to him, who include a self-identified Marxist, a decades-long member of the British Communist Party, and a defender of Joseph Stalin).

Just as disqualifying—though less remarked upon—is Corbyn’s attitude toward Islamist extremism. Take the most egregious example: the Islamic State. Corbyn does not long for the creation of a caliphate or imposition of sharia. However, he can only bring himself to condemn the Islamic State if, in the same breath, he lambasts what he sees as the other side of the coin: Western imperialists.

Corbyn sees such a moral equivalency between Islamist terrorist groups and Western governments that he cannot condemn the former without pointing to the flaws of the latter.

So Corbyn will concede that the Islamic State is “brutal, yes, some of what they have done is quite appalling” only at the same time as pointing out that “likewise, what the Americans did in Fallujah and other places is appalling.” It is the same with Britain’s own history.

In a debate in the House of Commons, Corbyn could only bring himself to say, “I have no support for ISIS whatsoever,” by raising British treatment of the Kenyan Mau Mau rebels six decades earlier, saying, “The way in which they had been treated by the British Army in Kenya in 1955 was disgusting.”

Corbyn does the same with al Qaeda. He is willing to concede that the 9/11 attacks were a tragedy only in the context of what he regards as other, equal tragedies—including Osama bin Laden’s death, the Iraq War, the “attack on Afghanistan,” the detention center at Guantánamo Bay, and the Bagram military prison.

Furthermore, if Britain and United States are not so morally superior, then retaliation against their policies becomes entirely understandable. Discussing the attacks in Washington and New York less than a month after 9/11, Corbyn told Parliament that “what goes around comes around.” It was time for “people in the United States … [to] think also about some of the regimes and friendships that they have spawned over the years,” he said.

Then, three days after al Qaeda’s suicide bombings in London in July 2005, Corbyn spoke at a Stop the War Coalition rally in the city to stress the reason that civilians there were being blown up on trains and buses was “because of the way we inflict an insecurity on so many other people around the world. We have to be very clear about that.”

It is a favorite Corbyn theme. At another Stop the War rally (before becoming leader of the Labour Party, attending Stop the War rallies constituted a significant part of Corbyn’s life), he said the Islamic State’s beheading of Alan Henning, a British aid worker, was “the price of jingoism.”

For groups regarded as less extreme than al Qaeda and the Islamic State, Corbyn has been less restrained—and often a vocal backer. In a 2009 speech in London, where he was addressing the Stop the War Coalition, Corbyn famously described Hamas and Hezbollah as his “friends.” 

He now says he regrets that statement, yet he has been friendly with those in Hamas’s orbit throughout his political life.

For example, he attended a 2012 conference in Qatar featuring Palestinian militants recently released by Israel in exchange for a captured soldier. Two of those speakers were Abdul Aziz Umar, convicted in Israel for his role in a 2003 suicide bombing in Jerusalem that killed seven people, and Husam Badran, a former head of Hamas’s military operations who had planned suicide bombings that killed more than 100 people. Corbyn found their contributions “fascinating and electrifying.”

Corbyn is also close to the British charity Interpal. While it operates legally in the United Kingdom, the United States designated it as terrorist group in August 2003 because it served to “provide support to Hamas and form part of its funding network in Europe.” (Interpal rejects the U.S. allegations and sues those in Britain who repeat them.)

Corbyn praised Interpal at a February 2013 conference and encouraged more donations to be made as they had “done such great practical work.” Corbyn calls the chair of Interpal, Ibrahim Hewitt, a “very good friend.” It’s a rather odd friendship for a progressive, as Hewitt has previously ranted about the evils of homosexuality and called for adulterers to be stoned to death.

And in November 2017, Corbyn attended a meeting held by Muslim Engagement and Development (MEND), a British nongovernmental organization focused on issues pertaining to Muslims, in Parliament to discuss Islamophobia. A well-publicized report documenting MEND’s wide-ranging ties to extremists led several members of Parliament to withdraw from the event, yet Corbyn made a point of turning up. In that context, Corbyn’s appearance was a highly symbolic gesture.

Corbyn is friendly with certain Islamist outfits because he thinks their anger is an understandable response to Western foreign policy. Yet he also supports conspiracy theorists who claim that it is not Islamist extremists behind terrorist attacks at all; in fact, it is the Jews.

For example, when the conspiratorial-minded British vicar Stephen Sizer was banned from social media for posting that Israel and Jewish conspirators were behind 9/11, Corbyn leapt to his defense. Corbyn claimed that Sizer was only being called out because he “dared to speak out against Zionism.”

Another person who believes that Jews were behind 9/11 is the Palestinian cleric and Hamas fundraiser Raed Salah. In 2011, the U.K. government attempted to deport Salah, who was visiting from Israel. Corbyn was quick to supportSalah, calling him an “honored citizen” who “represents his people extremely well” and inviting him to tea in Parliament. (Salah’s Jewish conspiracy theorizing does not end with 9/11; he has also repeated the blood libel that Jews used Christian children’s blood in religious ceremonies.)

When criticized for being too close to Islamist extremism, Corbyn inevitably responds with the same mantra: I abhor violence on all sides. We need a political settlement. We must have dialogue with those with whom we disagree.

None of this stands up to scrutiny. As his consistent covering for the IRA has demonstrated, he is perfectly relaxed about nonstate actors’ use of violence as long as it is for a cause—in that case, a united Ireland—with which he agrees. Despite protestations to the contrary, he is also completely disinterested in dialogue with those with whom he disagrees. It is why we always see him at conferences for Palestine and Stop the War rallies but never at the American Israel Public Affairs Committee or the Aspen Security Forum.

None of this really mattered as long as Corbyn was a fringe figure in British politics. However, he is now mainstream, and, as the Conservatives continue their fratricidal war over Brexit, he is tantalizingly close to No. 10 Downing St. The absurdity of this must be reiterated: Corbyn would not pass a rudimentary background check for a job as a low-level desk officer at the British security service MI5, and two of his top aides have not passed the background checks required to work in the House of Commons, meaning they have to enter as visitors. In fact, Corbyn’s links to the IRA are precisely why MI5 once had a file open on him. Yet soon it could be reporting to him.

This has clear consequences for Britain and its allies. One hopes that preexisting defense and intelligence arrangements—the Five Eyes intelligence-sharing relationship and hosting of U.S. military bases—are robust enough to survive Corbyn, although the health of the U.K.-Saudi intelligence-sharing relationship would be less certain, given that Corbyn is also an outspoken critic of Riyadh.

Corbyn’s criticisms of Saudi Arabia’s abysmal human rights record are entirely understandable. Yet one of the primary responsibilities of being prime minister is national security, and as former Prime Minister David Cameron said in October 2015 when discussing this conundrum, “We receive from [Saudi Arabia] important intelligence and security information that keeps us safe. … The reason we have the relationship is our own national security.” May, the current prime minister, has made the same point.

However, presuming Corbyn can win a workable majority in Parliament, Britain would no longer be such a reliable ally to the United States on various defense and foreign-policy matters. The United Kingdom may remain in NATO, but it will certainly not increase defense spending. It will not support any U.S. military operations, no matter where and no matter their worth. Corbyn’s track record is clear.

He did not support the war in Afghanistan. He voted against U.K. involvement in the Iraq War in 2003, against U.K. airstrikes on Bashar al-Assad in 2013, and against U.K. airstrikes on the Islamic State in December 2015. It is also perfectly clear from his public comments that Corbyn would refuse to carry out drone strikes against terrorists based overseas and planning attacks on British soil.

It’s doubtful that the role of prime minister would instill a sense of responsibility in Corbyn: Why should it? He is 69 years old and has dedicated his life to trying to radically transform the state. There is little reason for him to change his opinion now, when he is more popular than at any point in his life. What he believes as Labour leader is what he has always believed as an obscure Parliament backbencher, and it is what he would believe as prime minister.

Whether there was much appetite for this kind of politics among the British people was once an absurd proposition. Yet what once seemed absurd now seems not only possible; it seems probable. The man who has spent decades blaming the British state for the terrorist attacks it has suffered could soon be implementing the radical policies he believes will avoid the next one. Unfortunately, al Qaeda and the Islamic State are unlikely to suddenly take Britain off their target list simply because there’s an anti-imperialist firebrand in No. 10.