British Labour leader, Jeremy Corbyn is Israel’s most dangerous enemy in the Western European mainstream. He has a long record of anti-Israel incitement. Corbyn may well become British prime minister in the next parliamentary election. It is likely that he will surround himself with other extremist Israel-haters.The major public discussion over the past two and a half years about antisemitism in the Labour Party has overshadowed Corbyn’s anti-Israel incitement as well as his expressions of sympathy for genocidal Arab terrorists. At Labour’s annual conference in September, dominated by Corbyn’s supporters, an anti-Israeli motion was adopted by an overwhelming majority. It condemned Israel for the Palestinian casualties at the Gaza border since April and called for an international investigation of the situation. The motion furthermore requested a halt of UK arms sales to Israel. In his keynote speech at the conference, Corbyn condemned the continuing Israeli occupation as well as the Palestinian casualties at the Gaza border. He also repeated that if he becomes prime minister his government will immediately recognize a Palestinian state. Observers said that there were many Palestinian flags at the conference and no British ones.Several of Corbyn’s most senior associates are also long time Israel inciters. The powerful Shadow Chancellor, John McDonnell, spoke in 2012 at a far-left rally where he said that Israel was attempting a genocide against the Palestinians. In 2008, McDonnell was a lead signatory of a parliamentary motion that welcomed the founding of the International Jewish anti-Zionist Network (IJAN).Current polls indicate that a Corbyn-led government is a distinct possibility. The conservative government’s poor handling of the Brexit negotiations has probably helped Labour more than anything Corbyn and his colleagues have done. While the next parliamentary elections are scheduled for 2022, an early election due to the crisis around Brexit is a possibility.The chances of the moderate Labourites demoting Corbyn and his supporters from the leadership of the party are minimal. Since he was elected as leader in 2015, Corbyn and Momentum, his main supporters’ extreme left movement, have increasingly strengthened their grip on the party. Iain McNicol, a moderate resigned as general secretary, the most senior employee of the party in February 2018. He was replaced by a Corbynite, Jennie Formby. Several other key staff positions are now held by Corbyn supporters.Recently elections for the party’s governing body, the National Executive Council (NEC), were held. All nine members elected belonged to Momentum, and non-Momentum candidates got far less votes than those elected. Yasmin Dar, who received the most votes is seen in a 2017 film clip celebrating the Iranian Revolution at the Islamic center in Manchester.It may take Corbyn more time to gain full control of the parliamentary party as the great majority of MPs are moderates. Joan Ryan, the Chair of Labour Friends of Israel, has been deselected by her local party. The same has happened to MPs Gavin Shuker and Chris Leslie.Yet if too many moderates are deselected by their local parties some of them may run as independents or even as members of a new party. The latter might then collaborate with the third largest party, the Liberal Democrats. In the UK’s parliamentary system, there is only one election round. The candidate who receives the most votes in any one constituency is elected. If a deselected candidate runs against an official Labour pro-Corbynite candidate, the vote is likely to be split. As a result Labour may lose a number of its current seats.Is there anything Israel’s allies can do to make it more difficult for a Corbyn-controlled Labour to rise to power? So far, two possibilities have emerged. The first one derives from an opinion by the British law firm, WLegal. Under current US legislation, sanctions against Corbyn are possible as he is a supporter of a terror organization. Actions to achieve this would have to be taken now, as the US is unlikely to act against Corbyn if he becomes prime minister.A second issue which can be promoted outside the UK is publicizing the fact that if Corbyn comes to power he will receive access to highly classified intelligence from the British Security Services. Furthermore, it is unlikely that all intelligence can be withheld from his extremist associates who hold key positions in his administration.Would foreign governments be comfortable with such a situation? Would they want intelligence normally shared with allies to fall into the hands of the likes of Corbyn, McDonnell or Labour’s chief strategist, who is a supporter of the genocidal Hamas movement? What about Corbyn’s senior policy adviser, an ex-communist from whom British parliamentary security has withheld access to the Commons for a year already, or Corbyn’s private secretary, who after nine months of vetting by security services has not yet received access to the parliament? The problem already exists; whatever foreign intelligence has been shared with the UK will be accessible to Corbyn if he becomes prime minister.Once this information is spread outside the UK, British media are likely to pick up on this issue. That will inject additional pressure into the public debate over the risks to the country if a Corbyn-led Labour Party wins the next parliamentary election.Dr. Manfred Gerstenfeld is the emeritus Chairman of the Jerusalem Center for Public Affairs. He was given the Lifetime Achievement Award by the Journal for the Study of Antisemitism, and the International Leadership Award by the Simon Wiesenthal Center.