Joshua Bowles, 29, was sentenced to a minimum of 13 years behind bars for the "premeditated, targeted and vicious" knife attack at a leisure centre.

Bowles, who had two knives, punched and stabbed the woman repeatedly at the centre three miles from the agency's base in Cheltenham, Gloucestershire, on 9 March.

The Old Bailey judge, Mrs Justice Cheema-Grubb, found it was a "politically motivated attack" driven by "anger and resentment" towards GCHQ and women.

After the stabbing, the former computer software coding developer said he targeted his victim because he could not handle the "murky waters of ethics" and "the power that the American NSA [National Security Agency] have and the things they do".

Bowles, of Welwyn Mews, Cheltenham, pleaded guilty to the attempted murder of the woman, referred to by the code number 99230.

He also admitted assaulting a man who attempted to intervene, causing him actual bodily harm.

Prosecutor Duncan Penny KC said it was a "pre-meditated, targeted and vicious attack on an unarmed woman".

He told the court: "That woman was a United States government employee working in the United Kingdom.

"She was attacked by a man who was carrying two knives, and she was stabbed three times outside, and in the reception area of, a leisure centre in Cheltenham.

"Her selection as the target for this attack was entirely and solely associated with her role as a US government employee in the National Security Agency (NSA) of the United States."

The woman had been at a leisure centre in Cheltenham playing netball on 9 March, and was followed as she left with her friend, who was a fellow US national known as 25869.

When she heard someone say "Excuse me", she turned round and was punched repeatedly in the face. She then fought back, and her friend hit him with a bag and told him to leave her alone.

Alex Fuentes was on his way to play football and was punched in the face when he asked the defendant "what's going on?".

It was his intervention that meant the two women could run back to the leisure centre - pursued by Bowles.

Mr Penny said: "The CCTV footage shows the defendant holding a knife and lunging towards 99230, who was trying to back away. She describes that 'It felt like he hated me... his focus was me'."

The victim of the attack was left with a 6cm cut to her lower abdomen, a 2cm wound to the front of her chest and a 2cm wound to her right thigh.

She had to spend a week in hospital and told the court in a victim impact statement that she did not remember ever encountering or speaking to her attacker before.

She described how she had been studying for a master's degree, planned to learn windsurfing with her boyfriend and had entered a half-marathon.

"He has had a profound effect on me and completely changed my life. It is very difficult to explain to people just how awful it has been," the victim added.

"I went from being in the best shape I have ever been in, to the weakest I have ever been. I felt like my organs had been rearranged. I was hunted by him and I don't know why."

Bowles, who has Asperger's syndrome, said in a statement to police he targeted her because she was a US spy.

He said: "Due to the size and resourcing, American intelligence represents the largest contributor within the intelligence community so made sense as the symbolic target. I consider GCHQ just as guilty."

His lawyer said his client expressed "profound regret, remorse and shame at what he has done", adding he rejected any connections to terrorism.

A GCHQ spokesperson said: "This was a shocking, unprovoked attack and its isolated nature does not make it any less upsetting. Our thoughts are with the victims and their families. GCHQ has been working closely with police during their investigation, and we welcome justice being done."