U.S. Defense Secretary Ashton Carter made the comment in a news conference in Kabul with Afghan President Ashraf Ghani, who has previously called on Obama to "re-examine" the withdrawal plan to ensure his country has the support it needs to maintain security gains.
Carter arrived in Afghanistan's capital on Saturday during his first foreign trip since being sworn in as defense secretary four days ago.
"Our priority now is to make sure this progress sticks. That is why President Obama is considering a number of options to reinforce our support for President Ghani's security strategy, including possible changes to the time line for our drawdown of U.S. troops," Carter said.
"That could mean taking another look at the timing and sequencing of base closures to ensure we have the right array of coalition capabilities to support our Afghan partners," he said.
After Ghani's election last year, Afghanistan and the United States signed a security agreement that allowed U.S. troops to stay in Afghanistan beyond the previous December 2014 deadline to withdraw.
Under the current plan, the United States ended its combat presence in Afghanistan in December, but nearly 11,000 troops remained at the start of 2015 for training and support roles.
American forces currently are expected to drop to 5,500 in 2016, and by 2017 the U.S. military presence is to scale down to what officials described as a "normal" embassy security contingent.
"Deadlines concentrate the mind. But deadlines should not be dogmas," Ghani said in the "60 Minutes" interview. He continued: "If both parties or, in this case, multiple partners, have done their best to achieve the objectives and progress is very real, then there should be willingness to re-examine a deadline."
Carter recently took over as secretary of defense
, replacing Chuck Hagel. The Senate confirmed Carter on February 12, and he sworn in on Tuesday.
Carter plans to meet with U.S. troops and other Afghan leaders during his Afghanistan trip Saturday and Sunday.
"I have seen reports of all kinds giving assessment of how things are going in Afghanistan and I'm just coming back into the government now and trying to wrap my mind around it," he said.
When asked about ISIS activity in Afghanistan, Carter replied: "I've seen the reports of people essentially rebranding themselves as ISIL here in Afghanistan as has occurred in other places. The reports I've seen still have them in small numbers and aspirational."
Carter, 60, is a respected technocrat
who served in a number of high-level positions at the Pentagon. He holds degrees in theoretical physics and medieval history from Yale and Oxford.
Hagel, a former Republican senator, resigned after less than two years on the job when he was unable to fully mesh with Obama's national security team at the White House.