WASHINGTON (Reuters) – The United States must make a long-term commitment to Afghanistan to stop security there from worsening further and prevent attacks on the West by militants based there, the outgoing commander of U.S. forces in Afghanistan said on Tuesday.

General John Campbell said in testimony before a congressional committee that while Afghan security forces had shown “uneven” performance in 2015 and faced major leadership problems, continued U.S. support for the Afghan government was needed to defeat the Taliban and other militant groups including al Qaeda and the Haqqani network.

“These are certainly not residual threats that would allow for a peaceful transition across Afghanistan,” Campbell said. “Ultimately the threats Afghanistan faces require our sustained attention and forward presence.”

Campbell has commanded U.S. and international forces in Afghanistan for the past 18 months and is expected to retire. President Barack Obama has chosen Lieutenant General John Nicholson to replace Campbell.

A blunt Pentagon report released in December said the security situation in Afghanistan deteriorated in the second half of 2015, with the Taliban staging more attacks and inflicting far more casualties on Afghan forces.

The security situation prompted Obama to announce in October that the United States would maintain a force of about 9,800 troops in Afghanistan through most of 2016, instead of drawing down to an embassy-based presence by 2017.

Of 407 district centers in Afghanistan, 26 are under insurgent control or influence, Campbell said, with another 94 district centers viewed as at risk at any given time.

Campbell praised Obama’s decision to maintain a U.S. troop presence throughout most of this year, and said the United States was developing a five-year vision that would avoid the traditional year-to-year planning mindset.

“Now more than ever, the United States should not waver on Afghanistan,” Campbell said. “If we do not make deliberate, measured adjustments, 2016 is at risk of being no better, and possibly worse than 2015.”

(Reporting by Yeganeh Torbati; Editing by Steve Orlofsky)