Terrorist: Junaid Hussain, 21, is a former computer hacker turned jihadi who joined ISIS after fleeing his home city of Birmingham in 2013. He has been named as Number Three on a Pentagon 'kill list'

A young computer hacker from Birmingham has been named as Number Three on the Pentagon’s ‘kill list’ of key ISIS operatives.

Junaid Hussain, 21, fled to Syria in July 2013 and is now believed to be leading the ‘Cyber Caliphate’, ISIS’ own branch of hackers.

US officials said there is an ‘intense’ desire to assassinate Hussain, who operates under the alias Abu Hussain al-Britani and was jailed in 2012 for stealing personal information of Tony Blair.

Only Mohammed Emwazi, the hostage killer known as Jihadi John, and the group’s leader Abu Bakr al-Baghdadi are higher on the list, reported The Sunday Times.

After fleeing the UK, when he was on police bail for an alleged violent disorder offence, Hussain has risen rapidly through the ISIS ranks.

He married 45-year-old Sally Jones, a former punk rocker from Chatham, Kent, who converted to Islam and fled to Syria with her 10-year-old son.

Jones, who now uses the nomme de guerre Umm Hussain Al-Britani, is believed to have snuck into Syria at the end of last year after an online romance with Hussain.

She is suspected of leading the violent all-female ISIS contingent, known as the Khanssaa Brigade. The group imposes strict Sharia law in the de facto capital of the so-called Islamic State, Raqqa.

The couple, who have been dubbed Mr and Mr Terror, also reportedly used Twitter and the hashtag #LondonAttack in May to incite terror in Britain.

US officials believe he is behind the online radicalisation of at least one of the two gunmen who opened fire at a Prophet Mohammed cartoon competition in Garland, Texas, in May.

Threat: Junaid Hussain (pictured left and right) uses the alias Abu Hussain al-Britani, and was previously jailed in 2012 for stealing the personal information of Tony Blair

Past life: Former punk rocker Sally Jones married Hussain, after fleeing to Syria with her 10-year-old son, after an online relationship with Hussain

Transformation: Sally Jones, 45, goes by the nomme de guerre Umm Hussain Al-Britani and is believed to lead the all-female ISIS contingent known as the Khanssaa Brigade

Sickening: Just seconds after the first shots were fired in Garland, Hussain posted what appeared to be inside information about the attack - revealing two men were behind it and that an art exhibit was targeted

Hussain was reportedly in contact with one of the ‘lone wolf’ gunmen before the attack, and tweeted congratulations to his ‘Muslim brothers’ within minutes of the first shots fired.

One of the gunmen, Elton Simpson, earlier used his ‘Sharia is the Light’ account to post a series of messages about an impending attack and urged followers to subscribe to Hussain’s Twitter account.

Hussain later tweeted: ‘You ain’t seen nothing yet.’

More recently, Hussain was identified as the main suspect in the hacking of Twitter and Facebook accounts belonging to U.S. Central Command.

Since arriving in Syria, Hussain has threatened to raise the ISIS flag over ’10 Downing Street and the White House’ and to empty British bank accounts to fund terrorism in the Middle East.

Hacked: More recently Hussain was identified as the main suspect in the hacking of Twitter and Facebook accounts belonging to U.S. Central Command

Terror: Posted to the Twitter account was this ominous threat to American soldiers which follows a similar video warning posted by Abu Mohammed al Adnani, spokesman for ISIS

Threats: The Twitter hack posted the names, telephone numbers and home addresses of 4-Star US generals

He has also threatened to hack into the US stock markets, and circulated an apparent ‘hit list’ of US military personnel with their addresses and photographs online.

CNN reported that Hussain is also believed to have masterminded a hacking of the Pentagon’s computers in January.

Hussain and his wife were believed until recently to be living in the area of Raqqa.