US President Barack Obama is investigating a proposal to keep 5,000 troops in Afghanistan, an American senior official said.

A top US official declared that President Obama is considering leaving up to 5,000 U.S. troops in Afghanistan beyond 2016, diverging from his initial plan to scale back American forces by the time he leaves the White House.

Gen. Martin Dempsey before stepping down from his post as chairman of the Joint Chiefs of Staff on August introduced his new plan to focus on keeping 5,000 troops force primarily on counterterrorism operations against the Islamic State, al-Qaida and other direct threats to the United States.

Obama has not yet accepted nor rejected the proposal, but some officials say that the president plans to make a decision on it sometime soon.

Dempsey’s plan, however, has been the primary focus of White House debates in recent weeks.

It also envisions the United States maintaining a few bases, perhaps two or three that could be used as “lily pads” to launch strikes against groups that threaten the United States, senior defense and administration officials said.

Since Dempsey introduced the plan, the Taliban took control of the city of Kunduz. Though U.S. advisers have helped Afghan forces retake most of the city, the incident indicates that Afghan forces may not be strong enough to hold their ground against the Taliban when the U.S. leaves the country.

The new plan would mark a major shift for the president, who appears to have abandoned his goal of ending the wars in Iraq and Afghanistan and is now searching for some “acceptable equilibrium, some minimal level of involvement, that avoids catastrophic reversals,” said James Dobbins, who served as Obama’s special representative for Afghanistan and Pakistan in 2013 and 2014.

After hearing the initial proposal, Obama told his commander that he was open to keeping more troops in Afghanistan but wanted Dempsey to bring him a more detailed blueprint, senior administration and defense officials said.

Obama asked military commanders to work with intelligence officials to give him a better sense of the potential threat the Islamic State and al-Qaida posed in the region over the coming years.

The president also wanted a more detailed cost assessment of Dempsey’s proposal and the number of troops and civilians needed to support it.

While the Obama administration has been focusing on Dempsey’s plan, Gen. John Campbell, the commander of U.S. forces in Afghanistan, has also developed multiple options for leaving forces in Afghanistan beyond 2016, one of which involves keeping 7,000 U.S. troops in the region.