Hagel is in Kabul on a surprise visit, his first to Afghanistan since being appointed as defense secretary.
His last visit to the region was in 2008 with then-senator Obama, who was campaigning for the presidency.
The US defense chief has planned meetings with commanders as well as President Hamid Karzai, who has pushed for the downsizing of American troops despite the 66,000 that remain on the ground, according to Reuters.
"I need to better understand what's going on," Hagel told reporters as he flew to Kabul, adding his goal was to "make my own assessment and listen to our commanders."
"We have a lot of big issues and challenges ahead as we prepare for a responsible transition," he said, Agence France-Presse reported.
Chuck Hagel was confirmed February 26 and sworn in as defense secretary the next day. He will be highly influential in shaping the final phase of the Afghanistan war, including decisions about how many US soldiers to leave in the country post-withdrawal in 2014, Reuters pointed out.
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