ITN

Bradley Manning, the source of the massive WikiLeaks trove of secret disclosures, faces a possible maximum sentence of 136 years in military jail after he was convicted on Tuesday of most charges on which he stood trial.

Colonel Denise Lind, the military judge presiding over the court martial of the US soldier, delivered her verdict in curt and pointed language. "Guilty, guilty, guilty, guilty," she repeated over and over, as the reality of a prolonged prison sentence for Manning – on top of the three years he has already spent in detention – dawned.

The one ray of light in an otherwise bleak outcome for Manning was that he was found not guilty of the single most serious charge against him – that he knowingly "aided the enemy", in practice al-Qaida, by disclosing information to the WikiLeaks website that in turn made it accessible to all users including enemy groups.

Lind's decision to avoid setting a precedent by applying the swingeing "aiding the enemy" charge to an official leaker will invoke a sigh of relief from news organisations and civil liberties groups who had feared a guilty verdict would send a chill across public interest journalism.

The judge also found Manning not guilty of having leaked an encrypted copy of a video of a US air strike in the Farah province of Aghanistan in which many civilians died. Manning's defence team had argued vociferously that he was not the source of this video, though the soldier did admit to the later disclosure of an unencrypted version of the video and related documents.

Lind also accepted Manning's version of several of the key dates in the WikiLeaks disclosures, and took some of the edge from other less serious charges. But the overriding toughness of the verdict remains: the soldier was found guilty in their entirety of 17 out of the 22 counts against him, and of an amended version of four others.

The guilty verdicts included seven out of the eight counts brought under the Espionage Act. On these counts, Manning was accused of leaking the Afghan and Iraq war logs, embassy cables and Guantánamo files "with reason to believe such information could be used to the injury of the US or the advantage of any foreign nation". The 1917 act has previously been reserved largely for those who engage in spying as opposed to leaking; the seven convictions under the act are likely to be seen as a major stepping up of the US government's harsh crackdown on whistleblowing.

Manning was also found guilty of "wrongfully and wantonly" causing to be published on the internet intelligence belonging to the US, "having knowledge that intelligence published on the internet is accesible to the enemy". That guilty ruling could still have widest ramifications for news organisations working on investigations relating to US national security.

The verdict was condemned by human rights campaigners. Amnesty International's senior director of international law and policy, Widney Brown, said: "The government's priorities are upside down. The US government has refused to investigate credible allegations of torture and other crimes under international law despite overwhelming evidence.

"Yet they decided to prosecute Manning who it seems was trying to do the right thing – reveal credible evidence of unlawful behaviour by the government. You investigate and prosecute those who destroy the credibility of the government by engaging in acts such as torture which are prohibited under the US Constitution and in international law."

Ben Wizner, of the American Civil LIberties Union, said: "While we're relieved that Mr Manning was acquitted of the most dangerous charge, the ACLU has long held the view that leaks to the press in the public interest should not be prosecuted under the Espionage Act.

"Since he already pleaded guilty to charges of leaking information – which carry significant punishment – it seems clear that the government was seeking to intimidate anyone who might consider revealing valuable information in the future."

Julian Assange, the founder of Wikileaks, said in a statement from the Ecuadorian embassy in London, where he is sheltering from extradition to Sweden on suspicion of sex crimes, that the verdict set a "dangerous precedent" and was an "example of national security extremism".

In a statement to the Guardian, Manning's family expressed "deep thanks" to his civilian lawyer, David Coombs, who has worked on the case for three years. They added: "While we are obviously disappointed in today's verdicts, we are happy that Judge Lind agreed with us that Brad never intended to help America's enemies in any way. Brad loves his country and was proud to wear its uniform."

Once the counts are added up, the prospects for the Manning are bleak. Barring reduction of sentence for mitigation, which becomes the subject of another mini-trial dedicated to sentencing that starts tomorrow, Manning will face a substantial chunk of his adult life in military custody.

He has already spent 1,157 days in detention since his arrest in May 2010 – most recently in Fort Leavenworth in Kansas – which will be deducted from his eventual sentence.

A further 112 days will be taken off the sentence as part of a pre-trial ruling in which Lind compensated him for the excessively harsh treatment he endured at the Quantico marine base in Virginia between July 2010 and April 2011. He was kept on suicide watch for long stretches despite expert opinion from military psychiatrists who deemed him to be at low risk of self-harm, and at one point was forced to strip naked at night in conditions that the UN denounced as a form of torture.

Lind has indicated that she will go straight into the sentencing phase of the trial, in which both defence and prosecution lawyers will call new witnesses. This is being seen as the critical stage of the trial for Manning's defence: the soldier admitted months ago to being the source of the WikiLeaks disclosures, and much of the defence strategy has been focused on attempting to reduce his sentence through mitigation.

With that in mind, the soldier's main counsel, David Coombs, is likely to present evidence during the sentencing phase that Manning was in a fragile emotional state at the time he began leaking and was struggling with issues over his sexuality. In pre-trial hearings, the defence has argued that despite his at times erratic behaviour, the accused was offered very little support or counselling from his superiors at Forward Operating Base Hammer outside Baghdad.

The outcome will now be pored over by government agencies, lawyers, journalists and civil liberties groups for its implications for whistleblowing, investigative reporting and the guarding of state secrets in the digital age. By passing to WikiLeaks more than 700,000 documents, Manning became the first mass digital leaker in history, opening a whole new chapter in the age-old tug-of-war between government secrecy and the public's right to information in a democracy.

Among those who will also be closely analysing the verdict are Edward Snowden, the former NSA contractor who has disclosed the existence of secret government dragnets of the phone records of millions of Americans, who has indicated that the treatment of Manning was one reason for his decision to seek asylum in another country rather than face similar aggressive prosecution in America. The British government will also be dissecting the courtroom results after the Guardian disclosed that Manning is a joint British American citizen.

Another party that will be intimately engaged with the verdict is WikiLeaks, and its founder, Julian Assange. They have been the subject of a secret grand jury investigation in Virginia that has been looking into whether to prosecute them for their role in the Manning disclosures.

WikiLeaks and Assange were mentioned repeatedly during the trial by the US government which tried to prove that the anti-secrecy organisation had directly steered Manning in his leaking activities, an allegation strongly denied by the accused. Prosecutors drew heavily on still classified web conversations between Manning and an individual going by the name of "Press Association", whom the government alleges was Assange.