Egypt, Saudi Arabia, the United Arab Emirates and Bahrain severed diplomatic ties with Qatar on Monday over what they say is Doha's support of terrorist groups, widening the rift between some of the most powerful Arab countries.
Bahrain's Gulf Air said it will also suspend flights to and from Doha from Monday night, according to a statement.
Saudi Arabia and its allies announced they would withdraw their diplomatic staff from Qatar and closed their airspace to Qatar Airways, which suspended all flights to the Saudi kingdom, its neighbour.
The countries asked the Qatar's diplomats to leave their countries within 48 hours, and barred Qatari nationals from entering their states for 14 days and vice versa.
Qatar, which will host the 2022 World Cup and is home to some 10,000 American troops at a major U.S. military base, criticised the move as a "violation of its sovereignty".
Saudi Arabia also said Qatari troops would be pulled from the ongoing war in Yemen.
Bahrain also announced the severing of all diplomatic relations with Qatar "in order to preserve national security".
But for now Qatar's ruler appears unfazed.
Saudi Arabia, Egypt and the UAE all declared it a "terrorist group" after a Brotherhood government, led by Mohamed Morsi, won democratic elections in Egypt before being overthrown by the military in 2013.
Jane Kinninmont, a senior research fellow at London's Chatham House, said the renewed tensions were not clearly linked to "something new that Qatar has done".
The campaign aims to force non-Arab states to take sides and "persuade the Trump administration to come down hard on Qatar because of its refusal to join the anti-Iranian Saudi bandwagon and its ties to Islamist and militant groups", Dorsey wrote in a briefing paper. Eight months later, they returned their ambassadors as Qatar forced some Brotherhood members to leave the country and quieted others.
In the time since, Qatar repeatedly and strongly denied it funds extremist groups. Western officials also have accused Qatar of allowing or even encouraging funding of Sunni extremists like al-Qaida's branch in Syria, once known as the Nusra Front.
Shi'ite-majority Bahrain, home to the US Fifth Fleet, has intensified a crackdown on dissent since US President Donald Trump's visit last month.
It's a surprising move given the religious and cultural ties between many of those countries, as well as the fact that Emirates, Etihad and Qatar airlines have banded together in the Open Skies Agreements fight against the U.S.' big three of American, Delta and United. "Our relationship is extremely good".