John McAfee warned World War Three will be fought on a cyber-battlefield and he claimed ISIS terrorist could defeat the West by hacking cyber networks.

The security developer added the U.S. is 'defenseless' against such attacks.

World War Three will be a cyber war that the 'woefully underprepared' U.S. may lose to ISIS, a leading computer security expert has warned.

Describing the U.S. reliance on war machines and troops as outdated, John McAfee claims terrorist hackers could turn such equipment against us in a nightmarish 'doomsday' scenario.

In his column for the International Business Times, Mr McAfee said ISIS was actively recruiting hackers, while China and North Korea have already established programmes devoted to 'weaponised computing'.

He wrote: 'Our arsenal of bullets, bombs, tanks, planes, boats, missiles and our nuclear capabilities are rivalled by few, and likely exceeded by none.

'None of this matters in a cyber-war – a fact that could damage us when our weapons and equipment are turned against us using computers.'

Mr McAfee is a pioneer of cyber security, having created the anti-virus software that still bears his name in the late 1980s before later selling it to Intel.

In his column, he added that as long as the U.S. was unable to protect its cyber networks and the infrastructure connected to them - such as power grids, nuclear power stations, planes, cars and the finance industry - we would remain susceptible to hackers.

'These will be the weapons of cyber war – turned against us in a perversion of their intended purpose,' he wrote.

The full scale of ISIS cyber-attack capabilities was laid bare last month when extremists, apparently operating at the behest of ISIS's digital arm, hacked thousands of Twitter accounts.

In what experts described as a worrying escalation of the global cyber war, details of more than 54,000 Twitter accounts, including passwords, were posted online.

The extremists also posted hacked personal details, including mobile phone numbers, of the heads of the CIA, the FBI and America's National Security Agency, according to Daily Mail.

A group called Cyber Caliphate, set up by ISIS terrorist  Junaid Hussain from Birmingham, urged its followers to take control of the accounts to spread ISIS propaganda.

Hussain led ISIS's computer hacking division before he was killed by a US drone in a joint operation with the UK in August.

Junaid Hussain + Sally Jones

His widow, mother-of-two Sally Jones from Kent – known as 'Mrs Terror' – is on a Government list of the most dangerous British recruiters for ISIS.

However since Hussain's death, Cyber Caliphate, which briefly took control of a Pentagon-owned Twitter account in January, has kept a low online profile.

Mr McAfee's warning comes as the global cyber war escalates with hacktivists Anonymous last month declaring war on ISIS.

The hacking group promised to hunt down terrorists online following the terrorist attacks in Paris which left 130 people dead.

Anonymous's declaration of war came in a video posted on the group's French YouTube page shortly after the Paris attacks, were they warned the terror group to 'expect us', vowing to hunt down those responsible online and expose them.

Wearing the group's signature Guy Fawkes mask, a spokesman says in French: 'Anonymous from all over the world will hunt you down.

'You should know that we will find you and we will not let you go. We will launch the biggest operation ever against you. Expect massive cyber attacks. War is declared. Get prepared.'

Anonymous already publish and update a list of Twitter accounts they claim spread propaganda in support of ISIS, a list which has now increased to 5,500.

Sally Jones from Kent – known as Mrs Terror

However, as supporters and detractors of ISIS alike have pointed out that terrorists simply have to set up new accounts when their Twitter is shut down or exposed.

In 2012, Mr McAfee was living in Belize, where he claimed to have exposed high-level corruption before fleeing while being sought by police for questioning about a suspected murder.

He was later deported to the U.S. from Guatamala, where he is now running a campaign for the 2016 Presidency.