Almost two decades after the catastrophic 9/11 attacks, al-Qaeda seems capable of mounting similar terrorist strikes involving hijacked airplanes. Despite the relentless pounding that the terrorist organisation has received at the hands of the U.S. and its international allies, the recent focus on the Islamic State (ISIS) appears to have given the arch-terrorist group the necessary breathing space to reorganise. Currently, al-Qaeda groups or affiliates are active in Afghanistan, Pakistan, Syria, Libya, and Yemen, among other countries.

In an interview with the British newspaper The Sunday Times, Ben Wallace, a security minister in the British Government — the U.S. equivalent would be an Under-Secretary — warned about the threat of a resurgent al-Qaeda.

“Al-Qaeda sat quietly in the corner and tried to work out what the 21st century looked like, while Isis [sic] became the latest terrorist boy band, but they have not gone away,” said Wallace.

In order to combat this emerging threat, the British Government has been investing millions (at the moment the sum is around $31 million, but it is expected to rise) on research projects that intent to safeguard commercial airliners from hitherto uncommon explosives and insider attacks. Wallace’s reference to insider threats raises the question of how well commercial aviation companies screen their employees, both the crew members and support personnel? He said that if terrorists aren’t able to gain access to an airplane through the “front door” it is logical for them to try alternative methods or the “back door.”

“Aviation is still a blue riband event for these terrorists. Al-Qaeda are resurgent. They have reorganised,” said the British Government official. “They are pushing more and more plots towards Europe and have become familiar with new methods and still aspire aviation attacks,” he added. Wallace also said that British law enforcement and intelligence have prevented 13 terrorist attacks in the last few months.

What is, then, this “back door”? It could, for example, be a strike on a taxing airplane with a drone. Only recently, Gatwick Airport, which is the second largest airport in the United Kingdom when it comes to passenger and cargo traffic, was closed for almost two days because a drone was spotted near the runway. The British military has been deployed to ensure security, and the airport reopened. But the drone’s operators are still unknown to the authorities. The runways and berthing spots of major airports are packed with aircraft of all sizes, buses, trucks, and all sorts of miscellaneous airport vehicles. An airplane undergoing refueling would be a plump target for a small drone carrying some sort of an explosive device.