The US government will have to prove that the WikiLeaks source, Bradley Manning, had "reason to believe" that his disclosure of state secrets could be harmful to the US and beneficial to foreign nations, the judge presiding over the soldier's court martial ruled on Wednesday.

The ruling from Colonel Denise Lind, sitting in a military court at Fort Meade in Maryland, raises the burden of proof for the prosecutors who are trying to have the US soldier jailed for life for his actions in passing hundreds of thousands of classified state documents to the anti-secrecy website WikiLeaks. Manning has pleaded guilty to the leak, but only to lesser charges that carry an upper sentence of 20 years in military jail.

He has pleaded not guilty to the most serious charge, that he knowingly "aided the enemy". The charge carries a theoretical death sentence, but the prosecution has indicated it will seek life in military custody instead.

Manning is set to go to full court martial on 3 June, with the trial expected to last for 12 weeks. The scale of the WikiLeaks breach of US intelligence – including war logs from Iraq and Afghanistan, videos of US helicopter attacks, as well as a mountain of diplomatic cables from around the world – coupled with the seriousness of the charges, will ensure the trial will be the most high-profile prosecution of a leaker in a generation.

In a separate ruling, Lind has given the prosecution the green light to call witnesses who will testify that the WikiLeaks material actually reached "the enemy". The defence, led by a civilian lawyer, David Coombs, had tried to preclude any evidence relating to the end-use of the leaked documents and videos on grounds that it was irrelevant and potentially prejudicial to Manning.

But the judge found that it was relevant, particularly to the key prosecution accusation that the soldier "aided the enemy". She listed a number of hostile groups as "the enemy" in this case, including al-Qaida, al-Qaida in the Arabian peninsula, and an unspecified number of other organisations referred to only by code name.

Lind stressed that to be found guilty, Manning would have to be shown beyond reasonable doubt to have knowingly dealt with an enemy of the US. The crime could not be inadvertently or accidentally committed, she said.

Her ruling opens the door to the appearance of "John Doe" as a prosecution witness. He is an unnamed member of the team that killed Osama bin Laden in Abbottabad in Pakistan in 2011, and is presumed to be an existing or former member of the US Navy Seals.

The court has heard that the witness found three items of digital media at Bin Laden's compound which he removed. Later analysis revealed that the items contained WikiLeaks material that had been requested directly by the al-Qaida leader for his perusal, the prosecution will seek to prove.

The conditions under which that witness will give evidence have yet to be finalised by the judge. The defense department and the CIA have demanded absolute anonymity for the individual, to the extent that he will appear in disguise in a closed session of the court at a secret location and with no media or public present.

But Manning's defence lawyers are protesting about the restrictions on cross-examination and discovery, arguing that they cannot properly represent their client if they are withheld access to the witness.

The question of how to handle classified information during the trial continues to exercise Lind and both sets of lawyers. Paradoxically, though most of the classified material that will be referred to in testimony is now in the public domain courtesy of WikiLeaks, it is still considered a US state secret and any mention of it has to be redacted or discussed in closed court.

Early next month the judge has ordered a two-day "dry run" of a sample witness who will testify and submit to cross-examination in a private session. The purpose of the experiment will be to see whether there are alternatives to holding all sensitive testimony behind closed doors, the judge said.

The issue of courtroom security also came up when Lind issued a stern warning to the media and the public benches at the start of the hearing. She made clear her displeasure at the recent unauthorised recording of Manning's personal statement to the court that was published on the internet.

The recording was a violation of court martial rules, Lind said. "I have not ordered people in the media operation center to be screened for recording devices, and I hope I will not have to."