© Graham TidyThe car stuck in the gates at the US Embassy.
The Australian Federal Police bomb response unit attended the Yarralumla complex after ACT Policing, Fire and Rescue and Ambulance crews were called about 6pm.
Investigators said it was too early to tell what circumstances had led to the accident and five-hour police operation, but neither the vehicle or the embassy security gates were extensively damaged.
No explosives were found in the orange Peugeot hatchback which bore Queensland number plates.
Acting Superintendent Darren Rath said the man had been taken to the ACT Watch House and remained in custody ahead of possible charges.
"The search has been conducted and we are confident there is no issue," Superintendent Rath told journalists outside the embassy.
"Investigations are ongoing as to the circumstances which saw the vehicle collided into the premises and I don't want to pre-empt them."
He said US Ambassador Jeffrey Bleich was in residence during the incident and had been briefed throughout.
"Certain protocols were enacted of course, but I can't say whether that is termed lock down," he said.
He stressed the involvement of the AFP bomb response unit was precautionary due to the incident taking place at a diplomatic mission.
Staff at the US Embassy, one of the most heavily protected diplomatic buildings in the nation's capital, are expected to make a statement about the incident on Thursday.
Roads including Perth Avenue and Moonah Place were roads were closed during the incident.
Items removed from the boot of the car included a laundry basket and various pieces of men's clothing.
"The security here [at the embassy] did exactly what it was supposed to do," Superintendent Rath said.
An ACT Policing spokeswoman said the man was expected to face the ACT Magistrates Court and was uninjured in the incident.
Brilliant distraction for what's happening in politics at the moment. Talk about an elephant in the room! And a subject that nobody seem to be talking about.