On Sunday, the Taliban claimed the northern city of Kunduz, freeing dozens of Taliban fighters from the city prison. As US troops continue to withdraw from Afghanistan, the Taliban is seizing regional capitals, advancing toward Afghan cities such as Kandahar and Herat, and gaining “strategic momentum.” And in July, President Biden announced the formal end of the US combat mission in Iraq but added that the United States would continue to “train” and “assist” Iraqi security forces.

The United States has spent billions of dollars and the better part of two decades trying to organize, train, equip, advise and assist the Afghan National Army and the Iraqi Army, along with other Afghan and Iraqi security forces.

Why is it so hard to build stronger militaries in partner countries?

The United States rarely initiates large-scale security force assistance projects in countries governed by political and military leaders who are highly motivated to build better militaries. Researchers point out that leaders facing societal upheaval, insurgency and civil war often prioritize preventing coups, consolidating political power, personal enrichment or personal survival above the strength of their nation’s military.

In practice, this means that instead of taking steps to strengthen their militaries, leaders may promote loyal officers rather than competent ones, ignore or encourage corruption and neglect or discourage rigorous training. They might welcome huge infusions of cash, equipment and assistance from the United States, while simultaneously ignoring US advice and implementing policies that keep their militaries weak.

Fundamentally, then, the core challenge of security assistance for the United States is the challenge of influence. The United States builds better militaries when recipient leaders take US military advice along with US assistance — and US security assistance fails when US influence fails.

The US relies on persuasion — which rarely works

Most scholars who look at this challenge argue that partners’ competing interests are too strong and US bargaining power too weak for the United States to effectively wield carrots and sticks. In practice, however, bargaining power has little to do with it.

Through interviews and archival research, I found that US military advisers rarely attempt to use (or even consider using) incentives to influence partner leaders. A dominant theme in US military doctrine for advisory missions is persuasion. US military advisers are taught to build rapport and trust with local leaders. They are coached to lead by example (“show what right looks like”) and to inspire partners to emulate the US approach.

Military advisers aim to persuade counterparts to follow their advice by explaining the logic behind it, and by encouraging them to take pride in the professionalization of their nation’s military. If their counterparts ignore their advice, advisers are instructed to prioritize rapport above cooperation.

The US military’s reliance on persuasion is puzzling. Security force assistance is well-suited to carrot-and-stick-style leverage. Not only are recipients usually highly dependent on the United States, but the United States can build the credibility necessary for effective bargaining by turning the assistance dial up or down — or by targeting specific units, individuals or contingencies — over the course of a long-term relationship.

Indeed, a growing number of scholars and practitioners have advocated for introducing conditions into US military assistance. For instance, the US military could tie assistance to a specific division to its progress addressing corruption, or it could make aid installments contingent on improved leadership at the battalion level.

So why rely on persuasion?

Civilian leaders in Washington delegate military assistance projects — like those in Vietnam, Iraq and Afghanistan — almost entirely to the US military. Although Washington would decide whether to withdraw US assistance to a partner country entirely, in the day-to-day of assistance interactions, US military advisers (from the general officers seeking to influence partner political leaders to the tactical advisers paired with partner battalion commanders) can decide whether and how to apply pressure or modify support.

The US military, like most large bureaucracies, tends to pursue its bureaucratic interests and to stick to patterns of behavior that advance them. When the US military settles on a preferred way of doing business that does not advance objectives set in Washington, it often takes a major push from Washington for the military to change tack.

These bureaucratic and organizational dynamics help explain why US military advisers stick with the persuasion approach, even as their local counterparts ignore their advice and implement policies that undermine the advisory effort.

Adding conditions to security force assistance may be an effective tool of influence. But a threat by military advisers to curtail assistance to partner units could disrupt the US military’s own security assistance routines. By focusing instead on maintaining rapport, the US military can keep its training, advising and equipping processes moving without interruption. Maintaining positive interpersonal relationships with the partner also helps to avoid the kind of spats that could draw negative attention in Washington.

To encourage Washington to keep the assistance taps open while staying out of its business, the military may play down the partner’s fundamental lack of resolve — a challenge that more money and more time can’t fix. Instead, reports to Washington often emphasize overall progress and good relations with the partner, while flagging discrete areas, such as poor logistical capabilities, that could benefit from additional funding.

The buck stops with Washington

Civilian leaders authorize the US military’s efforts to build foreign militaries in the context of government failure, societal upheaval, insurgency and civil war. Misconceptions of military assistance as a narrow, technical challenge, entrenched norms of civilian deference to the military, and a preference to show progress combine to weaken the civilian oversight and direction that might otherwise guide course correction.

From the fall of Saigon, to the fall of Mosul, to the Taliban’s latest gains across Afghanistan, the story of the longest, least successful US wars is also a story of the US struggle to build effective local militaries. There’s a logic to providing security force assistance — improving the capacity of partner militaries to manage their own backyards means the US military should be able to shift its own weight to higher priorities. Uncooperative partners and the US military’s reliance on rapport-based persuasion, however, stand in the way.

Rachel Tecott (@racheltecott) is an assistant professor at the US Naval War College. She received her PhD '21 from the MIT Department of Political Science. The views presented do not reflect official positions of the Naval War College, the Department of the Navy or the Defense Department.