The Australian government is telling travellers not to fly to Riyadh, in Saudi Arabia, after three attacks on airports that left 12 dead and more than 300 injured this week.
The capital's King Khalid Airport and other infrastructure have been targeted by drones and missiles since a Saudi-led coalition launched a major military offensive against Houthi rebels in neighbouring Yemen.
The Iran-backed Houthis claimed responsibility for the earlier attacks, which began Wednesday, local time.
Operations at King Khalid Airport have been suspended due to security reasons, causing hundreds of flights to be cancelled.
Here's what you need to know.
What happened?
The first attack, targeting two airports in Saudi Arabia took place on Wednesday, local time.
Yemen's Iran-aligned Houthis said they had attacked King Khalid and Abha airports with ballistic missiles and drones in retaliation to Saudi-backed airstrikes on Sanaa Airport in Yemen.
One Sudanese national was killed at King Khalid Airport and two foreign nationals were killed at Abha airport.
On Thursday, local time, Saudi Arabia's civil aviation authority said three Saudi nationals were killed, including a pilot, and several people were injured after King Khalid Airport and an aircraft were struck.
The authority said the injuries ranged from minor to severe, and the attacks caused material damage, adding that airport operations had resumed and air traffic had returned to normal.
The plane that was hit was parked on the tarmac at the time.
The third attack on Saturday killed four Saudis, a Palestinian, two people from Bangladesh and one person each from the US, Jordan, Syria, Sudan and Egypt, according to Saudi Arabia's civil aviation authority.
Reuters has reported that more than 309 people are injured.
Hospitals were flooded with wounded brought by ambulance and helicopter, people briefed on the matter said. Some were in a critical condition.
Saturday's attack, the deadliest in the kingdom in more than a decade, occurred without warning, with no alert issued by Saudi Arabia's threat warning system.
An injured traveller told Reuters they saw something fly across the sky outside the airport before part of the ceiling near a departure gate collapsed.
The US embassy in Riyadh said it was "aware of attacks" and "strongly recommends all US citizens avoid this airport and surrounding areas".
What happened to flights?
All flights to and from Riyadh are currently suspended or have been diverted.
Houthi attacks on Thursday and earlier in the week had already prompted a number of carriers to suspend or cancel services to the Saudi capital.
The airport had a heavy police presence, with all entrances blocked, and lights around the complex were dimmed.
Flights diverted elsewhere, the air traffic tracking website Flightradar24 tracker said.
Countries including the US, Britain, Germany, Australia and Canada warned citizens to avoid the airport.
The Australian Federal Government's Smart Traveller website urged travellers to reconsider the need to travel to Saudi Arabia, in updated advice published today.
"We now advise do not travel to King Khalid International Airport in Riyadh due to recent security incidents, which are disrupting airport operations," it read.
"If you choose to travel, do not depart for King Khalid International Airport until you have reconfirmed your flight with your airline or travel provider.
"Minimise your time at the airport."
Are more attacks expected?
The attack — the latest of several in the past week on the airport — is expected to increase Saudi pressure on allies including the US to provide military support for the kingdom, which has seemingly tried to avoid all-out war with the Houthis.
Shortly after the attack on Saturday afternoon, US President Donald Trump said he was evaluating whether the US should join Saudi strikes against the rebels.
"We may, we're going to look at it," he said.
"We just found out about the recent attack.
"So we'll make a decision. We move very quickly."
Trump later Saturday said he planned to speak to Crown Prince Mohammed bin Salman.
The Saudi-led coalition fighting the Houthis blamed them for the attack, calling it a "fully-fledged war crime" and vowing a firm response.
When will flights resume?
There has been no indication of when the airport in Riyadh will be back up and running.
The Houthis this week warned global airlines "for the last time" about the potential consequences of operating in Saudi airspace, which they described as a theatre for their military operations.
Before the latest attack, Air India, FlyDubai, Lufthansa Group and Pakistan International Airlines were among airlines suspending flights to and from Riyadh and other Saudi airports for varying periods.
The European Union Aviation Safety Agency had expanded its guidance on Saudi airspace, noting the Houthi's ability to strike targets deeper inside the kingdom, including Riyadh, and a "greater focus on aviation infrastructure".
What about travel to the Middle East in general?
The situation in the Middle East is still unpredictable and escalation in regional conflict can happen at any time, the Smart Traveller website said.
The website has rated destinations by level, lowering it to level two, which is: "Exercise a high degree of caution" for Qatar and the United Arab Emirates.
It says to avoid non-essential travel including transit to countries at level three: "Consider your need to travel".
These countries are:
- Bahrain
- Israel
- Jordan
- Kuwait
- Oman
- Saudi Arabia
Smart Traveller says to avoid all travel to countries at Level 4: "Do not travel".
These are:
- Iran
- Iraq
- Lebanon
- Palestine
- Syria
- Yemen