At least 1,000 U.S. troops will be in Afghanistan until early next year because of a slower-than-expected force commitment from NATO allies, Defense Secretary Chuck Hagel told The New York Times Saturday.

The sluggish response from NATO allies is blamed on Afghanistan's delay in signing a long-term security agreement.

Hamid Karzai, the former president, had refused to sign the deal a year ago. Since then, the controversy over the presidential election kept the deal from moving forward. But the Afghan Parliament eventually formally ratified the agreements, after Ghani signed, and some of the coalition nations have since been reassured and able to commit troops.

Hagel said that the extra deployment will serve only to meet personnel requirements necessary to maintain bases in the country.

Originally, the agreement was to keep 9,800 troops, but the extra commitment reflects on the successful efforts of President Ashraf Ghani to create a better relationship with the U.S.

The long-term timeline to withdraw U.S. troops from Afghanistan remains intact, Hagel said, and there will be only 5,500 overall by the end of 2015.

Hagel resigned last month, but on his recent unannounced trip to Kabul–the fourth as defense secretary–he said that Afghanistan was able to defend itself with its own troops. Ashton Carter, a former deputy defense secretary, has been nominated by President Barack Obama to succeed Hagel.

But despite Hagel's confidence in the country's ability, the Taliban has clearly proven its determination to undermine the Afghan forces. This year it has claimed more lives than any previous year.

RT.com reported that the announcement to keep extra troops in Afghanistan is coming just weeks before the official end to the combat mission, which began in 2001.

The NATO-led mission has had a presence in the country since 2001 and was slated to end soon, but the attacks from the Taliban have spurred a cautious approach and warranted extra troops.

The spike in Taliban attacks is the highest since 2001 and includes a number of bloody attacks on the capital.