Saudi Arabia and three other Arab nations have severed diplomatic and transport ties with Qatar, claiming Doha’s regional policies fuel extremism and terrorism. The unprecedented attempt to isolate the Gulf state includes Egypt, the United Arab Emirates and Bahrain, and escalates a dispute over Qatar’s support for political Islamist groups and perceptions that Doha is open to closer ties with Iran, Saudi Arabia’s arch-rival. Citing an official source, the Saudi news agency said the kingdom was cutting ties for the “protection of national security from the dangers of terrorism and extremism”. The four Arab states said they would close air and sea transport links with Qatar, the world’s top exporter of liquefied natural gas and the host of an important US military base in the Middle East. The three Gulf states have also blocked their nationals from travelling to Qatar and given Qataris two weeks to leave their countries. They said they would pursue legal avenues in an attempt to block friendly countries and companies transiting to and from Qatar across their airspace. The closure of Qatar’s only land border with Saudi Arabia threatens food supplies to the import dependent state, which is set to host the World Cup football tournament in 2022.