Several countries have accused Qatar of supporting Islamist groups, including the Muslim Brotherhood. Gulf states have demanded that Qataris leave their countries and return home.
Arab states cut diplomatic ties with Qatar
On Monday, Saudi Arabia, Bahrain, the United Arab Emirates (UAE) and Egypt cut ties with Qatar over concerns that the country has supported extremism. Yemen, Libya and Maldives later followed suit. The decisions plunged Qatar into chaos and ignited the biggest diplomatic crisis in the Gulf since the 1991 war against Iraq.
Egypt's Foreign Ministry gave Qatar's ambassador to Cairo 48 hours to leave the country and ordered its envoy in Doha to return within the same period. Bahrain also recalled its ambassador and ordered Qatari diplomats to leave within two days. Saudi Arabia closed its border and cut off air and sea links with the Arab nation, saying it aimed to protect itself from "the dangers of terrorism and extremism."
Meanwhile, the UAE accused Qatar of "destabilizing" the region with its "support, funding and embrace of terrorist, extremist and sectarian organizations," while Cairo accused Qatar of supporting "terrorist" groups such as the Muslim Brotherhood.
Qatar hosts the largest US airbase in the region, which is crucial to the fight against the Islamic State group.
Doha rebuffs accusations
Officials in Qatar, meanwhile, suspended all flights to Saudi Arabia, the UAE, Egypt and Bahrain until further notice. Customers affected by the decision are being offered a refund.
The Gulf nation also announced that it was in touch with FIFA, international soccer's governing body, with regards to the 2022 World Cup. FIFA did not elaborate on how the World Cup might be affected.
Qatari officials said the crisis would "not affect the normal lives of citizens and residents."
"The measures are unjustified and based on claims and allegations that have no basis in fact," the Foreign Ministry announced in a statement. "The aim is clear, and it is to impose guardianship on the state. This by itself is a violation of (Qatar's) sovereignty as a state."
'It's not good'
Business analysts have warned that, in addition to damaging Qatar's economy, the spat could also have adverse effects on the other countries involved. Stock markets in Qatar, Dubai and other Gulf centers fell following the announcement, with analysts warning of a potential knock-on effect. Qatar's stock exchange suffered losses of seven percent.
"Overall, it's not good. I don't think that the region has been in such turmoil so close to home. And I think everyone is speculating how far these steps will go forward," said Mohammed Ali Yasin, chief executive of Abu Dhabi's NBAD securities.
"Everyone is hoping that there will be intervention by wise people and things will cool down," Yasin said. "But what we have seen is a gradual escalation."
A Turkish official said President Recep Tayyip Erdogan was "actively involved" in efforts to resolve the diplomatic crisis. Deputy Prime Minister Numan Kurtulmus announced after a cabinet meeting that the government hoped that Erdogan's initiative would help overcome tensions, although he provided no details.
"The Middle East is not at a point where it can endure a new crisis," Kurtulmus said.
Fear about food shortages
Reza Nourani, the chairman of Iran's union of exporters of agricultural products, said Tehran could export food to Qatar by sea if Saudi Arabia and other Gulf countries were to impose any kind of trade embargo. Saudi Arabia already closed its land border with Qatar, through which the tiny Gulf nation imports most of its food.
Qataris stock up on food after Arab states cut ties
The Doha-based satellite news network Al-Jazeera reported that Qatar-bound trucks carrying food had begun lining up on the Saudi side of the border, apparently stranded, sparking a run on supermarkets.
Simon Mabon, international relations lecturer at Lancaster University and research associate at the UK-based Foreign Policy Centre, told DW that Donald Trump's visit to Saudi Arabia had effectively strengthened Gulf states' confidence, saying it appeared as if the US president had given them "carte blanche" to do what they want with Doha.
Qatar denies funding extremist groups. However, it remains a key patron of the Islamic Hamas movement, which rules the Gaza Strip, and also is seen to support the Muslim Brotherhood, a Sunni political group that is opposed to and may be trying to subvert monarchical rule, as is practiced in many nations of the Middle East.