"He went to the headquarters of the Mohmand Rifles and was given a briefing about military operations," said a government official in the region, who declined to be identified, referring to a regional paramilitary force.
Lou Fintor, a spokesman for the US embassy in Pakistsan, said: "He [Holbrooke] is in Pakistan to listen and learn the ground realities of this critically important country. This was the focus of his discussions."
He was referring to Holbrooke's talks on Tuesday with Asif Ali Zardari, the Pakistani president, General Ashfaq Kayani, the army chief, and other high-level political and security officials.
Holbrooke's appearance in Peshawar, the main city in Pakistan's northwest, was overshadowed by the death of a secular politician and six other people in a bomb attack on Wednesday.
Police said it appeared the bomb was hidden in a motorcycle and was detonated by remote control when a vehicle carrying Alam Zeb Khan passed.
The blast wounded the Awami National Party legislator, his bodyguard, two of his staff and three passers-by, a police officer said.
Khan later died at a hospital.
Reporting to Obama
Fintor, the US embassy spokesman, said Holbrooke would report his Pakistan findings to Obama and Hillary Clinton, the US secretary of state.
Holbrooke will also visit Afghanistan and India in the coming days.
The US administration is aiming to complete its review of Afghan strategy before Nato holds its next summit on April 2.
The US military has drawn up plans that could almost double the number of US troops there to about 60,000.
There are 37,000 US forces in Afghanistan at present, as part of a western military presence of about 70,000 troops.