A man accused of trespassing at the top secret Pine Gap Defence facility near Alice Springs has admitted he knew he was breaking a law.

But he defended his actions as necessary, saying Pine Gap was part of the murders of women and children.

Paul Douglas Christie, 44, was the only witness in his own defence in his NT Supreme Court trial.

Speaking to the jury, as he was representing himself, Christie argued that Pine Gap's activities - of which there is little official confirmation - justified his actions

"[Pine Gap] is not leading to an end of the war on terror but an escalation of the war on terror," he said.

"I'm a really proud Australian, I love this country and I want this country to be peaceful and harmonious, and I see Pine Gap as to be one of the biggest obstacles to that.

"I cannot bring evidence of that to this court because I will be shut down in the national interest."

The facility, outside of Alice Springs is off limits to the public. ( Supplied: Kristian Laemmle-Ruff )

Mr Christie also argued that he had been invited by the Indigenous Arrente people who are the custodians of the land around Alice Springs.

"There was no sovereignty ceded and I have lived and worked for a day where we have a treaty with the people so we can move forward," he said.

Under cross-examination by crown prosecutor Michael McHugh SC, Christie admitted he knew the area was prohibited by the Commonwealth Government.

"I was walking on a land that was governed by a law I was breaking," he said.

Christie has pleaded not guilty to one charge of being in a prohibited area.

The court heard a person in a red hooded jacket was first spotted inside the facility, run jointly by Australia and the United States, on CCTV at 6:30am on October 3, 2016, and that Mr Christie was arrested 1.5km inside the facility from the northern boundary fence.

Accused Christie says God helped him get into Pine Gap

Earlier on Tuesday, the jury was shown a video of an interview the Australian Federal Police conducted with Mr Christie on the day of his arrest.

In it, Mr Christie was shown claiming that local Arrente Aboriginal elders had given him permission to enter Pine Gap.

"I was invited onto that land by the elder of the Arrente tribe," Mr Christie said in the interview.

"I was given permission to walk the land by the Arrente people, to pray and sing for the children and I did that with their permission and their blessing and their support."

The AFP officers asked Mr Christie in the video how he had gotten through a perimeter fence surrounding the facility.

"I didn't see any fence or barrier that obstructed me in any way," he replied.

"Everything just opened up. It was like the light just took away all barriers."

When asked if anyone had helped him gain entry to the base, Mr Christie replied: "God".

He repeatedly claimed he was fighting against a "war culture" and described Pine Gap as a "facility of death".

When he was arrested he was found with a Tibetan singing bowl, a silver goblet, a ceremonial rattle, a red cockatoo feather, a topographical map of the area and a pocket knife.

Mr Christie is facing a maximum sentence of seven years in jail if found guilty.