Dubai (AFP) - A deadly attack by Yemen's Huthi rebels on the United Arab Emirates marks a new phase in a seven-year civil war that has claimed hundreds of thousands of lives.
Here are some key questions and answers after Monday's drone and missile assault:
What happened?
Two Indians and a Pakistani were killed in a fuel-tank explosion near storage facilities of oil giant ADNOC, sending smoke and flames billowing into the air.
A fire also broke out in a construction area of Abu Dhabi airport.
Police said "small flying objects" were found at both sites, pointing to a deliberate attack using drones -- a hallmark of Yemen's Iran-backed Huthi rebels.
The rebels later claimed the attack and said there could be more to come, warning UAE residents to stay away from "vital installations".
Why attack Abu Dhabi?
The UAE is a member of the Saudi-led coalition that has been fighting the rebels since 2015.Although it announced a troop withdrawal from Yemen in 2019, it has remained involved by supporting and training forces there.
It is no coincidence that the Huthis' attack followed their defeat in Yemen's Shabwa province to the UAE-trained Giants Brigade, which dealt a blow to the rebels hopes of capturing the key city of Marib in the neighbouring governorate.
"The battle of Shabwa has changed the equation of the conflict in Yemen," said Majid Al-Madhaji, a researcher at the Sanaa Center for Strategic Studies.
Al-Madhaji said the Huthis were "anxious", and had launched the Abu Dhabi attacks "to send this military message in the heart of the UAE".
The Huthis have repeatedly threatened to target the UAE, and claimed to have carried attacks in 2018 which were never acknowledged by the wealthy Gulf country.
"Many are not surprised by the attack, Ansar Allah had repeated threats to target UAE and today they delivered on that promise," said Mohammad Al Basha, a Yemen expert for research group Navanti, referring to the Huthi movement by its formal name.
The attack also came two weeks after the Huthis captured a UAE-flagged ship and its international crew in the Red Sea, saying it was carrying military equipment.
How did they do it?
The Huthis regularly target neighbouring Saudi Arabia with drones and missiles, but this attack appears to have traversed hundreds of kilometres (miles) of Saudi desert that separate Yemen from UAE.
The Huthis said they had used Quds 2 cruise missiles to hit the Musaffah refinery and Abu Dhabi airport, and also used Sammad-3 long-range drones.
They have a wide range of military equipment and weapons, including tanks and ballistic missiles, which they seized from Yemeni army stores after taking the capital Sanaa in 2014.
The Huthis also say they make their own drones, which they showed off as part of a military display in March last year in Sanaa.
Saudi Arabia and the United States have long accused Iran of supplying military hardware to the Huthis.Iran denies the charge.
What happens next?
The coalition responded with air strikes on the Yemeni capital late on Monday, killing several people, including the head of the Huthis' air force academy.
In turn, the UAE will be on edge for further assaults by the Huthis, particularly against its oil facilities and airports.
The rebels claimed they also attempted an attack on Monday on Dubai airport, a major transport hub.
But while it has backed the pro-government Yemeni Giant Brigades force, the UAE scaled back its involvement over two years ago and may be reluctant to get dragged in again, experts say.
"The UAE will not rush to a knee-jerk reaction.It has invested heavily in Yemen, particularly in new political and military infrastructure in the south," said Elisabeth Kendall, a researcher at Oxford University.
"It is unlikely to veer from its long-term strategy, for example by scaling up its own troop presence in Yemen again, on the basis of a provocation."
