Qatar diplomatic crisis: What you need to know
The tiny, oil- and gas-rich state of Qatar has been cut off and isolated by some of the Arab world's most powerful countries, which have accused it of supporting terrorist groups.
The dramatic move comes after years of tension between Qatar and its Gulf neighbours, in particular Saudi Arabia.
The effects are already being felt - in Qatari food stores, international airspace, the global oil market and elsewhere.
What's this all about?
Qatar has long practised an ambitious foreign policy with different priorities to its neighbours. But there are two key issues which have angered them.
One is Qatar's support for regional Islamist groups, including the Muslim Brotherhood, which is designated a terrorist group by some Gulf countries.
The other is its relations with Shia-led Iran - Sunni-ruled Saudi Arabia's arch-rival for influence in the region.
These issues came to a head late last month, when Qatar blamed hackers for a story on its state news agency website that quoted the emir as criticising US "hostility" towards Iran and calling the Islamic Republic a "big power in the stabilisation of the region".
The incident provided a spark for regional retaliation against Qatar, which said it was the victim of a "campaign of lies".
So, who has cut ties with Qatar?
In a co-ordinated move, Bahrain, Saudi Arabia, the United Arab Emirates (UAE), and Egypt withdrew their ambassadors from Qatar.
Yemen, the Maldives and Libya's eastern-based government all later followed suit.
Saudi Arabia, the UAE and Bahrain have given all Qatari nationals two weeks to leave their territory. The three countries have also banned their citizens from travelling to Qatar.
Does Qatar support terrorist groups?
While Qatar is a member of the US-led multinational coalition against so-called Islamic State (IS), the Qatari government has repeatedly denied accusations from Iraqi Shia leaders that it provided financial support to the jihadist group.
Qatar - and Saudi Arabia for that matter - has given money and weapons to hardline Islamist rebel factions fighting Bashar al-Assad in Syria.
Qatar though denies accusations of links to the al-Qaeda-linked jihadist alliance, Hayat Tahrir al-Sham.
Another militant group, the Afghan Taliban, has an office in Doha, Qatar's capital.
What impact could the crisis have?
To sum up: Flights, food and football.
Many airlines have suspended flights to and from Doha.
The national carrier, Qatar Airways, is also facing problems because it will be unable to carry out dozens of daily flights to major Gulf cities. Its flights to other destinations will have to take detours because it has been barred from large areas of airspace.
About 40% of Qatar's food is believed to come in through its land border with Saudi Arabia - which has been closed. Already people are rushing to shops to stock up on supplies.
There are many major construction projects underway in Qatar - not least eight stadiums for football's 2022 World Cup. The Saudi border closure could affect the supply of materials, and delay projects.
What about all the foreign workers living there?
Hundreds of thousands of people have flooded into Qatar in recent years to work - swelling its population to 2.7 million from 700,000 in 2003.
If Egypt were to ban its nationals from travelling to or residing in Qatar, that could have a major effect. About 180,000 Egyptians are estimated to be living there, with many working in engineering, medicine, law and construction.
There are signs that workers from other countries unconnected to the diplomatic spat could also be affected.
The Philippines - which counts upwards of 200,000 nationals in Qatar - says it will stop sending workers out of fears the crisis could worsen.
How important is Saudi Arabia in all of this?
Analysts say the decision to punish Qatar is likely to have been driven by Saudi Arabia, its large and powerful neighbour to the west.
Relations have been strained for years, and deteriorated in 2013 as they backed opposing sides in Egypt after the military ousted the country's first democratically-elected President, Mohammed Morsi - a leader of the Muslim Brotherhood.
The following year, Saudi Arabia, Bahrain and the UAE withdrew their ambassadors from Qatar in protest at its alleged interference in their affairs.
Although relations with Saudi Arabia appeared to have improved since then, the conciliatory comments towards Iran alleged to have come from Qatar's emir will have angered Riyadh.
Announcing its decision to cut off Qatar, the kingdom pointed to what it said was Qatar's collaboration with "Iranian-backed terrorist groups" in its restive eastern region of Qatif and in Bahrain, where security forces have cracked down on Shia protesters demanding greater political rights and an end to discrimination.
Analysts say Saudi Arabia may also feel emboldened to move against Qatar in the wake of a visit to Riyadh by US President Donald Trump, who called on Muslim nations to unite against terrorism.
What have reports of a huge ransom got to do with it?
There are claims that another reason for Gulf anger is a ransom of up to $1bn (£770m) that Qatar allegedly paid to secure the release of royal family members kidnapped while hunting in southern Iraq.
According to the Financial Times, the ransom was paid in April to an al-Qaeda affiliate in Syria, Shia militias and Iranian security officials - anathema to the Saudis.
Have any Gulf states not cut ties?
Two states in the six-member Gulf Cooperation Council (GCC) have not cut ties with Qatar - Kuwait and Oman.
Kuwait has offered to mediate in the dispute.
What could happen next?
The question is whether Doha will change its policies and positioning in response to the economic pain and disruption caused.
The diplomatic spat in 2014 ended after Qatar promised not to interfere in the internal affairs of other GCC states, and it could make more promises this time.
Foreign Minister Sheikh Mohammed bin Abdul Rahman Al Thani has called for "a dialogue of openness and honesty".
Turkey and Iran have also called for diplomacy to end the latest crisis.