BRUSSELS — World leaders are expected to approve plans in coming weeks that would keep a number of key NATO bases in Afghanistan open despite prior plans to have them shuttered in conjunction with a planned reduction of troops, a senior NATO diplomat said Wednesday.

The move provides President Obama flexibility in the event he holds off on his current decision to reduce U.S. troop levels by the end of 2016. In the past year, a resurgent Taliban has retaken large swaths of territory in the country and put pressure on Afghan forces.

According to the diplomat, who spoke to a small group of reporters on the condition of anonymity because the announcements had not yet been made publicly, the decision is expected to be made at the upcoming Warsaw summit in July.

The number of bases in the plan was not immediately clear, but it “gives us additional adaptability” in Afghanistan, the diplomat said.

NATO Secretary General Jens Stoltenberg indicated during a news conference Wednesday that NATO is still finalizing future plans and troop numbers into 2017 but believes keeping the additional bases will allow the alliance to have a “flexible regional approach.”

In Warsaw, NATO countries are expected to make a number of key decisions regarding the state of the alliance and the future of its mission in Afghanistan. According to the diplomat, NATO is expected to announce that it will be able to maintain its mission in Afghanistan through 2020, as the 28 NATO leaders are expected to contribute $5 billion apiece to buoy Afghan security forces.

Obama had initially planned to slash all but a small number of troops in Afghanistan by the outset of 2016. Large gains by the Taliban in 2015, however, prompted him to retain roughly 9,800 troops throughout the year. By the end of 2016, the troop numbers are slated to be reduced to 5,500. With that reduction, four key bases — including American hubs in the east and south — were meant to close. In the north, German troops would withdraw, as would Italian forces in the west.

According to the diplomat, those bases will remain open despite the planned reduction in troop levels. U.S. forces, though initially slated to consolidate in Kabul and Bagram by the end of 2016, will continue to maintain a presence in Jalalabad and Kandahar, the diplomat said.

The diplomat added that other NATO countries’ commitment to the Afghanistan mission remains “steady.”

Currently there are roughly 9,800 U.S. troops in Afghanistan, 6,800 of them in support of Resolute Support, the NATO mission that is bolstering Afghan security forces throughout the country. By the end of 2016, the United States is slated to contribute only 3,400 troops to Resolute Support. The remaining roughly 2,000 troops will be dedicated to Freedom Sentinel, the U.S.-led counterterrorism mission aimed at rooting out al-Qaeda and the Islamic State’s new offshoot entrenched in the east of the country.

Last week, Obama approved additional authorities that would allow U.S. ground commanders in Afghanistan to strike Taliban targets in support of Afghan forces.

The move is a subtle change from prior directives that allowed U.S. airstrikes against the Taliban only in a limited set of situations. The new authorities will also allow U.S. forces to accompany regular Afghan troops on certain missions, something that hasn’t been permitted since the United States declared an end to combat operations in the country in 2014.