The scene at Ataturk International Airport on Wednesday was one of confusion as airlines grappled with the latest bans issued against travellers from predominantly Muslim-majority countries.
This time the US has banned larger electronic devices from carry-on baggage. And the UK has followed suit.
Different airlines in Istanbul were offering different advice to customers on Wednesday, adding to travellers' woes.
The US restrictions affect 10 airports in the Middle East and North Africa in response to unspecified terrorism threats.
Following the US ban, the British government announced its own cabin baggage ban on any electronic devices larger than a mobile phone on direct passenger flights from Turkey, Lebanon, Jordan, Egypt, Tunisia and Saudi Arabia.
TRT World's Oliver Whitfield-Miocic was at Ataturk International Airport to see what effect the bans were having.
Security experts question utility of bans
The new rules will force a rethink on fire safety concerns in consigning electronic devices to the hold, and some experts question whether the bans can improve passenger security.
US officials said the clampdown was a response to reports that militant groups want to smuggle explosive devices in electronic gadgets.
However, some experts are mystified. Matthew Finn, managing director at security consultants Augmentiq, said placing such devices in the hold, rather than in the cabin made little sense. That's because improvised explosive devices could be triggered via a variety of mechanisms, including a small mobile phone that would still be in the cabin.
"I imagine there must be some reliable intelligence that gives credibility to the threat; I just can’t see how this particular measure will make anything or anyone safer as a result," he said.
Bruce Schneier, security technologist and lecturer at the Kennedy School of Government at Harvard University, disagreed.
"Forcing it in the plane's hold would make it much harder to detonate, since the terrorist has to design an automatic mechanism rather than doing it manually," he said.
The regulations will require an abrupt change of thinking at airlines which have been focused until now on the threat of fire from batteries contained inside many of the electronic items.
In 2016, the United Nations' aviation arm, the International Civil Aviation Organization, prohibited shipments of lithium-ion batteries as cargo on passenger planes.
Scope of the ban questioned
"A partial ban targeting only few airlines in some countries will not protect passengers from a terrorist threat," said Ruben Morales, head of corporate safety at Hong Kong Airlines.
"Nowadays airlines are highly connected through alliances and codeshare agreements... Nothing prevents passengers from bringing their electronic devices onboard non-direct flights to the US from countries outside of the ban."
Senior aviation industry officials expressed confusion about the ban, but disruption was minimal compared to the announcement of a temporary ban on travellers from seven Muslim-majority countries in January; a move later overturned and revised.
The International Air Transport Association, said it was working with airline members and the Trump administration to better understand the new requirements.
US stands by ban
The ban would continue for the "foreseeable future," a US government official said on Tuesday, adding that it was possible it could be extended to other airports and other countries.
US officials say militant groups such as Yemen-based Al Qaeda in the Arabian Peninsula (AQAP) are known for innovative bomb designs, including burying them inside computers.
White House spokesman Sean Spicer declined to talk about the intelligence that prompted the new steps or explain why some countries and airports were targetted.