Here is a recap:
Simmering regional tensions boil over on June 5, 2017, when Saudi Arabia and its allies Bahrain, Egypt and the United Arab Emirates (UAE) announce almost simultaneously that they are severing diplomatic ties with Qatar.
They accuse Doha of supporting “terrorists” and being too close to Saudi Arabia’s Shiite archrival Iran — charges Qatar denies.
Land and maritime borders with the Gulf peninsula are shut, air links suspended and Qatari citizens expelled.
Riyadh says it acted to “protect its national security from the dangers of terrorism and extremism”.
In a country dependent on food imports, there is alarm over whether the border closures will lead to food shortages in Qatar.
Saudi Arabia also closes the Riyadh bureau of Qatari broadcaster Al Jazeera.
On June 22 the Saudi-led bloc sends Qatar a list of 13 demands, which include shutting down its Al Jazeera media network, curbing relations with Iran and closing a Turkish military base it hosts.
They give Qatar 10 days to comply.
After a two-day extension, Qatar says on July 4 the list is “unrealistic and is not actionable”.
Saudi Arabia and its allies threaten new sanctions.
On July 25 they unveil a “terrorist” blacklist of 18 groups and individuals suspected of links to Islamist extremists and to Qatar.
The blacklist later grows to include almost 90 names.
Saudi state media reports on September 8 that Qatar’s emir has called the Saudi crown prince to express interest in talks.
An initial positive response turns sour when the Saudis accuse Qatari media of incorrectly implying that the kingdom initiated the outreach.
On September 9 Saudi Arabia suspends any dialogue with Qatar.
Seeking support from outside the region, Qatar signs a series of defence deals with foreign powers.
In June Doha inks a $12-billion (10.4 billion euro) deal to buy US-made F-15 fighter jets.
In early December, it finalises contracts with France worth more than $13 billion, including the purchase of 12 French-built fighter jets and 50 Airbus passenger planes.
It also concludes a $8 billion deal with Britain to buy 24 Typhoon fighters.
In January 2018, it approves legislation allowing 100-percent foreign ownership in most sectors of its economy.
Previously reliant on its Gulf neighbours, it increasingly turns towards Iran and Turkey, particularly for food imports.
Shortly after the crisis unfolds, Ankara fast tracks the deployment of troops to its military base in Qatar — part of a 2014 bilateral defence agreement.
In January Qatar says fighter jets from the UAE, one of the boycotting countries, violated its airspace in December and early January.
The UAE later accuses Qatari fighter jets of “intercepting” two Emirati passenger planes en route to Bahrain, drawing a swift denial from Doha.
Both sides complain to the UN.
On April 10 US President Donald Trump receives the emir of Qatar, calling him “a friend of mine” and a “gentleman”, softening his tone after initially backing the Saudi-led bloc.
Emir Tamim bin Hamad Al-Thani uses the opportunity to say: “We do not and we will not tolerate people who fund terrorism.”
Trump also praises Qatar’s purchases of military equipment from the US, which has about 10,000 troops at an airbase outside Doha — its largest in the Middle East.