The court in the trial of Peru's disgraced former intelligence chief is to call on the director of the CIA to testify on his relationship with him.
Montesinos still has 60 trials pending
Vladimiro Montesinos is accused of involvement in the smuggling of 10,000 rifles from Jordan to members of the Colombian rebel group FARC.
Prosecutors have said that evidence shows Montesinos had CIA support.
But Montesinos' lawyer has denied any irregular relations with the CIA as well as the "gun-running" charges.
The director of the US intelligence service, George Tenet, will be called by the court at the request of Montesinos' defence lawyer, the trial judge said on Tuesday.
Robert Gorelick, the CIA Lima station chief in 1999 will also be called upon by the court, AFP news agency reported.
The alleged gun-running operation occurred just before a US crackdown on illegal drugs in Colombia backed by Peru in the late 1990s.
As de facto head of Peru's security services, Montesinos is accused of arming the Revolutionary Armed Forces of Colombia (FARC) - the very people Washington was targeting.
Montesinos denies the charges, but he could receive a 20-year jail sentence if found guilty.
He is already serving nine years in a high security naval base near Lima after being convicted for lesser offences and has yet to face other charges including alleged involvement in death squad killings.
The right hand man of former President Alberto Fujimori, Montesinos effectively ran Peru from the shadows throughout the 1990s, says our correspondent Hannah Hennessy.
He sparked the corruption scandal that brought down the government in 2000, when a video appeared apparently showing him bribing an opposition politician.