Aerial reconnaissance and attack drones have had a liberating effect on US military forces, but they are deeply hated by many people and their overuse could jeopardise Washington’s broader objectives, retired General Stanley McChrystal said on Monday.

McChrystal, who authored the US counterinsurgency strategy in Afghanistan, said use of drones had enabled him to carry out missions with smaller groups of special operations forces because the “eye in the sky” provided backup security.

“What scares me about drone strikes is how they are perceived around the world,” he said in an interview. “The resentment created by American use of unmanned strikes … is much greater than the average American appreciates. They are hated on a visceral level, even by people who’ve never seen one or seen the effects of one.”

McChrystal said the use of drones exacerbates a “perception of American arrogance that says, ‘Well we can fly where we want, we can shoot where we want, because we can.’”

Drones should be used in the context of an overall strategy, he said, and if their use threatens the broader goals or creates more problems than it solves, then you have to ask whether they are the right tool.

President Barack Obama’s heavy reliance on drones to wage war against al Qaeda in Afghanistan, Pakistan and elsewhere has provoked questions about the use of the aircraft and the legality of targeted killings.

Washington has not been swayed by the criticism and Obama nominated the official behind the campaign, top counterterrorism adviser John Brennan, to be the next CIA director.

McChrystal said he had known Brennan for about a decade and applauded the choice, saying “he’s got the trust of other key players, and that’s a very important commodity.”

McChrystal has conducted a series of media interviews to promote his memoir, “My Share of the Task,” which was released on Monday. In it he recounts his military career, including his time as head of US special forces and commander of international troops in Afghanistan.

Creeping mistrust

McChrystal wrote that Obama’s first year in office was marked by creeping mistrust between the White House and the Pentagon over Afghan war policy, with repeated requests for more troops fueling the suspicion.

McChrystal, who became the top US commander in Afghanistan during those months, said Obama was elected at a time when  General David McKiernan, then head of international forces, was seeking 30,000 more troops to stave off a Taliban resurgence, a request that had been on hold since the previous summer.

“It created an unwelcome dynamic,” McChrystal wrote. “In the eighth year of the war in Afghanistan, a new president found himself facing a time-sensitive decision.”

“The next 10 months saw the emergence of an unfortunate deficit of trust between the White House and the Department of Defense, largely arising from the decision-making process on Afghanistan,” he wrote. “To me it appeared unintentional on both sides. But over time, the effects were costly.”

Obama initially approved 17,000 additional troops, but the Pentagon soon had to come back to ask for 4,000 more. And when McChrystal became commander of international forces later that year, he conducted a strategic reassessment and sought 40,000 more.

The rising mistrust ultimately played a role in McChrystal’s resignation. In June 2010 the general stepped down after Rolling Stone magazine ran an article entitled “The Runaway General,” in which it quoted members of McChrystal’s staff disparaging top White House officials and allies. McChrystal was summoned back to Washington, where he resigned.

An investigation by the Department of Defense Inspector General concluded that not all of the events described in the Rolling Stone article had occurred as reported and there was insufficient evidence to conclude any Defense Department standards had been violated.

McChrystal, while expressing surprise about the “tone and direction” of the article, said he accepted responsibility for it and never had any question about the necessary response.

“I knew only one decision was right for the moment and for the mission. I didn’t try to figure out what others might do, no hero’s or mentor’s example came to mind. I called no one for advice,” wrote McChrystal, who now teaches leadership at Yale University and heads a leadership consulting group.