US Defence Secretary Chuck Hagel has arrived in Afghanistan on his first foreign trip in his new position as head of the Pentagon.
He told reporters travelling with him he wanted to see for himself "where we are in Afghanistan".
"I need to better understand what's going on," he said.
The new secretary's last trip to Afghanistan was in the summer of 2008 with then-Senator Barack Obama.
Mr Hagel said he was looking forward to "reacquainting" himself with President Hamid Karzai, although he has known the Afghan leader for more than a decade.
The former Republican senator who was sworn in on 27 February after a bitter fight with his own party in Congress, said his main priority was to thank the troops currently deployed there.
There are about 66,000 US military personal at present in the country. Early next year that figure will drop to 34,000. The question of how many international troops will remain after 2014 is still unknown.
The new head of the US defence department has arrived at a markedly tense point in the US-Afghan relationship.
Saturday was due to be the official handover of Bagram prison, although the event was postponed at the last minute without explanation, according to an Afghan military spokesman.
Control of Bagram has been a "deal-breaker" between the Obama administration and the Karzai-led government.
Kabul had made full ownership of the detention centre a condition of signing a long-term partnership agreement with the US.
In September 2012 the US handed over thousands of Afghan prisoners to Afghan security forces but maintained control of a few dozen foreign national detainees at the facility.
Also this weekend, President Karzai has set a deadline for all US special forces to leave Wardak province on Sunday.
The BBC has been told that the edict came as a complete surprise to many US officials. Wardak sits close to Kabul and any deterioration of security there would have a direct impact on the Afghan capital.
At the moment, sources say, negotiations are continuing but it appears that the Karzai government will soften its stance.