Islamists claiming allegiance to Islamic State have issued a threat against Heathrow, LAX and JFK airports, warning that one of them would be targeted over the July 4th weekend.

A transport minister has said that government is taking “all steps necessary to keep the public safe,” but advised continual vigilance by travellers.

The threat, made by a “pro-Islamic State Twitter account,” was picked up by non-governmental counter-terrorism organisation SITE Intelligence Group on Friday, who issued an alert, the Telegraph has reported.

The alert advised that the account had issued threats against planes “flying from Heathrow to the US” during the 4 July US Independence Day holiday weekend, and warned “there will be a device placed in either Heathrow, LAX [Los Angeles] or JFK [New York] airports”.

Transport minister Lord Ahmed of Wimbledon has urged the public to be cautious, saying: “We all need to be vigilant to the global threat of terrorism – in the UK we keep all aspects of aviation security under constant review and work closely with our international partners to mitigate risks.

“We will continue to take all steps necessary to keep the public safe, but for security reasons we do not comment in detail on specific measures or operational matters.”

Heathrow Airport has declined to comment on the threat, referring inquiries to the Department of Transport.

The threat comes just days after Islamist terrorists killed at least 41 people and injured as many as 230 in an attack at Istanbul’s Ataturk Airport. One attacker opened fire with an automatic weapon in the departures area, before all three assailants blew themselves up in the arrivals area, one floor below.

Police were firing on the men in an attempt to prevent the attack when the detonated their devices. It was the third suicide attack to take place in Istanbul this year.

Following the attack, Turkish President Recep Tayyip Erdogan called on “the international community, especially the Western countries including their administrations, parliaments, media organs and civil societies, to take a firm stand against terrorism.”

He added: “Make no mistake: For terrorist organizations, there is no difference between Istanbul and London, Ankara and Berlin, Izmir and Chicago or Antalya and Rome.”

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