Former UK Foreign Secretary William Hague has claimed that recent terrorist atrocities in Brussels show 'the need to crack' terrorist communications, citing strong encryption and the Edward Snowden leaks as contributing factors to ongoing intelligence failures across the globe.

"Because the perpetrators left no digital trail, we must change our approach to legitimate surveillance or lose ground in the long war to come," he wrote in The Telegraph. "The mobile phones [the Brussels terrorists] carried had evidently not been used before and showed no record of texts, chat or emails. Whatever means of co-ordination they used, it was sufficiently private or encrypted that the authorities do not seem to have been aware of it," he said.

According to Hague, terrorist groups like the so-called Islamic State (Isis) have become highly advanced at "communications discipline". This, he argues, helps to bolster coordinated attacks across Europe while staying under-the-radar of intelligence agencies.

"The care taken by the Brussels murderers to leave no digital trail is a sign of strict and thorough training, and one of many indications that the struggle against 'Islamist' terror will be the longest and most arduous of our modern battles with indiscriminate killing," he warned.

Recent suicide bombing attacks in Brussels were targeted at a central airport and an underground metro station and resulted in over 30 fatalities. Meanwhile, an attack in Paris last November left over 130 people dead and hundreds wounded after gunmen and suicide bombers hit a concert hall, a sport stadium and restaurants simultaneously.

In light of the escalating encryption argument between the FBI and Apple, strong cryptography quickly became one reason given as to why law enforcement was unable to foresee the incident. However, evidence has since emerged that showed how Isis-affiliated terrorists relied on pre-paid 'burner' phones over standard applications like WhatsApp or iMessage to stealthily communicate prior to the Paris attacks.

However Hague remained silent on criticism of burner handsets. Instead, he argued that intelligence failures leading up to atrocities in Brussels and Paris were partly to blame on the Edward Snowden revelations three years ago.

"Since Edward Snowden's leaks and allegations about Western intelligence-gathering in 2013, every mastermind of terrorism or organised crime has been alerted to the need to change or disguise their means of communication," he wrote. "All spy agencies hostile to democracies have been given a temporary advantage, including those in Russia, where Snowden now skulks." He added: "[UK intelligence agencies] have been hampered in recent years by the Snowden leaks, by the rise of widespread encryption by communications firms, and by developments in technology."

Former NSA-contractor Edward Snowden leaked a trove of classified documents that outlined a vast spying apparatus used by intelligences agencies including the NSA, FBI and GCHQ. Surveillance programmes such as Prism and Tempora were found to be scooping up communications and social media data on a massive scale.

Mass surveillance 'paranoia'

In any case, Hague dismissed accusations that governments in the US and UK conduct any form of 'mass surveillance'. Instead, he claimed, bulk collection is one sure-fire method of clamping down on terrorist activity. "[Data retention] is vital in order to see patterns in the behaviour of those who might join a cell such as the one in Brussels. And it can help us to spot them if they make a mistake," he asserted.

Referencing the ongoing scrutiny of the Investigatory Powers spying bill, Hague said: "Over the next few months, Parliament will engage in the centuries-old debate about how to balance privacy and security. It should recognise that collecting bulk data is not the same as mass surveillance, and learn a key lesson of Brussels: beating this terror will need every legitimate tool that a free society can employ."

Hague is not the first politician to publicly blame Snowden for failures of the intelligence agencies. Last November, London Mayer Boris Johnson said: "When the story of the Paris massacre is explained, I would like a better understanding of how so many operatives were able to conspire, and attack multiple locations, without some of their electronic chatter reaching the ears of the police. I want these people properly spied on, properly watched – and I bet you do, too."