WASHINGTON - The CIA has made plans to close its network of secret bases in Afghanistan and pull its personnel back to Kabul this summer, an unexpectedly abrupt withdrawal that the U.S. military fears will deprive it of vital intelligence while thousands of American troops remain in the country, U.S. officials said.

CIA Director John Brennan informed U.S. military commanders in March that his agency would start to shutter Afghan operations outside Kabul, the capital, removing CIA clandestine officers and analysts as well as National Security Agency specialists responsible for intercepting insurgents' communications, which have been a rich source of daily intelligence, the officials said.

Pentagon officials warn that the CIA drawdown is coming at a time when insurgent attacks normally intensify, after a winter lull. As a result, the plan has strained relations between the agency and military commanders in Kabul, the officials said.

Military is concerned

"They are beginning their own retrograde and they kind of sprung it on the military, which is raising concern," said a senior military official, who asked for anonymity because he was not authorized to discuss classified CIA plans.

Intelligence officials confirmed the drawdown would occur, but said the pace remained uncertain and no final plan had been approved.

They linked the move to the steady pullout of U.S. combat troops from America's longest war. Soldiers and Marines have provided protection and logistics support for intelligence-gathering outposts, which often are inside U.S. military facilities. Hundreds of those frontline military bases and camps have now closed, although dozens are still operating.

"The CIA footprint is entirely dependent on the military's," a senior U.S. official said Thursday.

"There is no stomach in the building for going out there on our own," said a former CIA operator who has spoken to current officers about the pullback. "We are not putting our people out there without U.S. forces."

John Maguire, who retired from the CIA in 2005 after 23 years as a case officer, noted that CIA officers on horseback were the first U.S. forces into Afghanistan after the terrorist attacks of Sept. 11, 2001. He criticized the spy service for the current drawdown.

Going it alone?

"There is ample evidence and a long historical record of the agency working alone in any number of difficult and dangerous places, and if they can't do it by themselves without the military, then they should close the organization," he said.

The CIA also plans this summer to stop paying the salaries of Afghan paramilitary forces that it has armed and trained for more than a decade to help fight the Taliban-led insurgency in the country's east, near the Pakistani border. It is unclear what will happen to the militias.

The Pentagon is trying to persuade the CIA to slow its withdrawal, arguing that keeping CIA and NSA operators in the field as long as possible would help prevent a surge in militant attacks before the end of the year, when most U.S. troops are due to leave.

About 33,000 U.S. troops remain in Afghanistan, down from a peak of 100,000 in 2011.

U.S. Marine Corps Gen. Joseph F. Dunford Jr., the top commander in Afghanistan, has offered to help the CIA close its intelligence-gathering installations and remove its equipment late this year. By taking on that task, he hopes to persuade the CIA to remain in the field until at least October, one of the officials said.

Pentagon officials also are exploring whether the military can take over financial support of the CIA-backed militias to keep the Afghans from leaving the fight or switching sides, officials said. Some of the frontline units already have been disbanded, according to a report in the Daily Beast.

Brennan told military officials that the CIA would be able to continue gathering intelligence and targeting militants even after pulling back to Kabul and the nearby Bagram Air Base, one official said.

The spy service already has sharply cut the pace of lethal drone strikes in Pakistan, flown from airfields in Afghanistan. One official said the agency was making plans to continue operating the armed drones on a much smaller scale, from Bagram.

Several al-Qaeda commanders, including the terrorist network's leader, Ayman al-Zawahiri, are believed to be hiding in northwestern Pakistan. The tribal belt also serves as a base for fighters from the Haqqani network, which is allied with the Taliban and has launched numerous attacks against U.S. and NATO forces in Afghanistan.

Brennan told the military that the CIA faced other priorities outside Afghanistan and Pakistan that were compelling it to redeploy staff, the official said.

The agency is increasingly focused on threats in Syria, Yemen, and parts of Africa as al-Qaeda has morphed into regional affiliates that are seen as more dangerous to the United States and its allies.