WASHINGTON >> With alarming frequency in recent years, thousands of U.S.-trained security forces in the Middle East, North Africa and South Asia have collapsed, stalled or defected, calling into question the effectiveness of the tens of billions of dollars spent by the United States on foreign military training programs, as well as a central tenet of the Obama administration’s approach to combating insurgencies.

The setbacks have been most pronounced in three countries that present the administration with some of its biggest challenges. The Pentagon-trained army and police in Iraq’s Anbar province, the heartland of the Islamic State militant group, have barely engaged its forces, while several thousand U.S.-backed government forces and militiamen in Afghanistan’s Kunduz province were forced to retreat last week when attacked by several hundred Taliban fighters. And in Syria, a $500 million Defense Department program to train local rebels to fight the Islamic State has produced only a handful of soldiers.

U.S.-trained forces face different problems in each place, some of which are out of the United States’ control. But what many of them have in common, U.S. military and counterterrorism officials say, is poor leadership, a lack of will and the need to function in the face of intractable political problems with little support. Without their U.S. advisers, many local forces have repeatedly shown an inability to fight.

"Our track record at building security forces over the past 15 years is miserable," said Karl W. Eikenberry, a former military commander and U.S. ambassador in Afghanistan.

The U.S. military has trained soldiers in scores of countries for decades. But after the terrorist attacks of Sept. 11, 2001, that mission jumped in ambition and scale, especially in Afghanistan and Iraq, where the ultimate goal was to replace the large U.S. armies deployed there.

The push to rebuild the Iraqi army that the United States disbanded after the 2003 invasion had largely succeeded by the time U.S. troops withdrew eight years later. But that $25 billion effort quickly crumbled after the Americans left, when the politicization of the army leadership under Prime Minister Nouri al-Maliki eroded the military’s effectiveness at all levels, U.S. officials said.

In Afghanistan, basic training typically included marksmanship, ambush drills and other counterterrorism skills. Before they could begin that, most new Afghan recruits also needed time-consuming literacy training so they could read the serial numbers on their weapons, or lessons on proper hygiene to prevent illnesses that would reduce their effectiveness in combat. Still, there were notable successes: Afghan special forces trained and advised by their U.S. counterparts proved to be especially capable fighters.

Then, in a commencement speech at the U.S. Military Academy in May 2014, President Barack Obama put the training of foreign troops at the center of his strategy for combating militant groups that threatened U.S. interests. The United States, he said, will no longer send large armies to fight those wars and, in the case of Afghanistan, would continue to withdraw the forces that are there. Instead, it will send small numbers of military trainers and advisers to help local forces, providing them with logistical, intelligence and other support.

"We have to develop a strategy," Obama said, "that expands our reach without sending forces that stretch our military too thin or stir up local resentments. We need partners to fight terrorists alongside us."

Expensive Failures

Obama’s approach has already endured several setbacks, but with no political appetite among most Republicans or Democrats to send in large numbers of U.S. troops, the administration is adjusting its strategy, often turning to regional allies for help in supporting local forces.

In northwest Africa, the United States has spent more than $600 million to combat Islamist militancy, with training programs stretching from Morocco to Chad. U.S. officials once heralded Mali’s military as an exemplary partner. But in 2012, battle-hardened Islamist fighters returned from combat in Libya to rout the military, including units trained by U.S. Special Forces. That defeat, followed by a coup led by a U.S.-trained officer, Capt. Amadou Haya Sanogo, astounded and embarrassed U.S. commanders. French, United Nations and European Union forces now carry out training and security missions in Mali.

In Yemen, U.S.-trained troops and counterterrorism forces largely disbanded when Houthi rebels overran the capital last year and forced the government into exile. The United States is now relying largely on a Saudi-led air campaign that has caused more than 1,000 civilian casualties.

More recently in Afghanistan, Iraq and Syria, the military campaigns against the Taliban and the Islamic State, also known as ISIS or ISIL, have made little headway. After acknowledging that only four or five U.S.-trained Syrian rebels were actually in the fight there, Pentagon officials said last week that they were suspending the movement of new recruits from Syria to Turkey and Jordan for training. The program suffered from a shortage of recruits willing to fight the Islamic State instead of the army of President Bashar Assad, a problem Obama noted at a news conference on Friday.

"I’m the first one to acknowledge it has not worked the way it was supposed to," he said. "A part of the reason, frankly, is because when we tried to get them to just focus on ISIL, the response we get back is, ‘How can we focus on ISIL when, every single day, we’re having barrel bombs and attacks from the regime?’"

In Afghanistan, the United States has spent about $65 billion to build the army and police forces. Even before last week’s setback in Kunduz, many Afghan forces were struggling to defeat the Taliban, partly because of what many senior commanders said had been a precipitous U.S. drawdown before Afghans were ready to be on their own. But how thousands of Afghan army, police and militia defenders could fare so poorly against a Taliban force that most local and military officials put only in the hundreds baffled and frustrated the Pentagon.

Shiites Step Back

A U.S. training program to strengthen the embattled security forces in Iraq has run aground, in part because the Iraqi government has provided far fewer recruits than anticipated, while many Shiite militiamen and soldiers who were fighting the Islamic State have left the battlefield and joined the exodus of migrants seeking new lives in Europe.

The reality is that Iraq’s Shiite majority seems to be settling in to a divided Iraq and increasingly questioning whether it is worth shedding Shiite blood in areas like Anbar province or Mosul, Iraq’s second-largest city, which the Islamic State captured in June 2014. The battle against the Islamic State is no longer the national priority it was a year ago, when the militants threatened Baghdad and the Shiite-majority south.

With those areas now largely secure, mostly because of the efforts of Iranian military advisers and their proxy militias, the Iraqi government is focused on other priorities — mostly the migrant crisis and street protests.

For the White House, which hoped to rely on a rehabilitated Iraqi army and Shiite militias to fight the Islamic State, this raises troubling questions and highlights the diverging interests of the United States and its partner.

Vali Nasr, dean of the School of Advanced International Studies at Johns Hopkins University and a former senior adviser at the State Department, said there was a deepening sense in Iraq that "ISIS is a Sunni problem, not a Shia problem." He said the prevailing belief now among Shiites was that saving Anbar was not worth "the blood of our children."

The United States and 16 allied countries have so far trained six Iraqi army brigades and 10 Kurdish peshmerga battalions, or about 12,000 troops, according to the Defense Department. About half of the army troops are now in the fight, with the others training on their equipment and soon to follow, U.S. military officials said.

One option now for the United States is to emphasize training and equipping Sunni tribal fighters, something the Obama administration has long sought to do. But while there are about 5,600 Sunni fighters in Anbar as part of the Popular Mobilization Forces, the umbrella group for the largely Shiite paramilitary forces, they have yet to prove themselves in combat.

An Iraqi official briefed on the military situation in Anbar, who spoke on the condition of anonymity because he was not authorized to talk to the news media, said, "I don’t think there is a sense of urgency anymore."

"Clearly, there is no progress," the official said. "Why there is no progress is what everyone is talking about. I don’t think there is any will among the Iraqi security forces and militias to fight. They are just not fighting."

Soldiers and militiamen, many of whom said they had not been paid in months, are dropping their weapons and heading for Europe.

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