Gordon Lubold , John Hudson

The Obama administration's controversial decision to swap five senior Taliban figures for the military's lone prisoner of war, Bowe Bergdahl, is putting new pressure on the White House to do more to free the three other American citizens who have been missing in Afghanistan or Pakistan for years but have drawn little attention in Washington.

The American civilians thought to be in captivity include Caitlin Coleman, an American citizen who, along with her Canadian-born husband Josh, disappeared in Afghanistan in October 2012. Coleman was pregnant and would have had a child by the following January; if the infant survived, he or she would be considered an American citizen. The third missing citizen is Warren Weinstein, 72, a government contractor who was doing work in Pakistan when he was kidnapped in August 2011. It was unclear from government officials Monday what the status of these Americans was or if active discussions were taking place to secure their release.

In a letter to President Obama Monday, Rep. Duncan Hunter, Jr., a California Republican, demanded to know why they weren't part of the deal in which Washington agreed to send five detainees from Guantánamo Bay, Cuba to Qatar in return for Bergdahl's release. Bergdahl, 28, had been held by militants since wandering off his tiny outpost in eastern Afghanistan in 2009.

"My understanding is that three other Americans remain in custody of militants aligned with the Taliban," Hunter wrote. "Should this still be the case, I would like to know why these individuals were not included in the negotiation that resulted in the release of five detainees from Guantánamo Bay." Hunter also urged the president to "expedite and exhaust ongoing lines of effort" to ensure the return of the three Americans, but was careful to stipulate that it should not be done by releasing additional detainees from Guantánamo Bay. There was no immediate response to the letter from the White House.

The deal, which has attracted growing criticism in recent days, has also raised new questions about the status of the other three Americans and whether the United States might part with additional detainees to secure their release. Upon hearing of the prisoner swap, the Weinstein family released a statement saying they were happy for the Bergdahls but hoped it would renew efforts to secure the release of their husband and father, grandfather and father-in-law. Weinstein has been held in Pakistan for more than 1,000 days, the statement said. The last "proof-of-life video" was provided to the United States in December, but it shows an ailing Weinstein who will turn 73 in July.

"Warren has dedicated his entire life to working on development and humanitarian aid projects that have improved the lives and livelihoods of countless people around the world," the statement said. "Like all families with loved ones held in captivity, we are desperate for his release before it's too late."

Bergdahl's release also raised questions about other Americans in captivity, including: US contractor Alan Gross, currently held in a Cuban prison; former FBI agent Bob Levinson, who disappeared from Iran's Kish Island while on a CIA mission; and Kenneth Bae, a South Korean with US citizenship convicted by North Korea for trying to overthrow the government. When asked if the prisoner exchange had any implications for their release, the State Department emphasised the importance of Bergdahl's service in the military, a factor that distinguishes his situation from Weinstein's as well.

"It's worth repeating, Sergeant Bergdahl ... is a member of the military who was detained during an armed conflict," State Department spokesperson Jen Psaki said. "That obviously is a unique circumstance. In any case, whether it's Alan Gross or Kenneth Bae or others who are detained American citizens, we take every step possible to make the case and to take steps to ensure their return home to the United States."

Despite the euphoria of having Bergdahl back safely in American hands - the missing soldier is currently at a US military medical facility in Landstuhl, Germany for unknown reasons - there has been much criticism of the swap. Republicans have derided Obama for in effect trading the five detainees for just one American prisoner of war. In addition, conservatives are arguing that the United States has set a dangerous precedent that could trigger kidnappings of other American service members. And it amounts to a violation of the oft-repeated American mantra that the United States doesn't negotiate with terrorists, they say.

The mysterious nature of Bergdahl's disappearance from a US military base in Helmand province in Afghanistan in 2009, in which it appears he may have wandered off the base or deserted his unit, feeds the storyline that the White House's play was ill-advised.

Some troops also feel deep ambivalence about Bergdahl's return. The facts about his disappearance that day remain murky. But if reports are true that he left voluntarily, perhaps to walk from Afghanistan to India in what could amount to deserting his unit, troops who live by a credo to "never leave a man behind" may begin to doubt if it was all worth it. 

Many veterans have been far more direct. Nathan Bradley Bethea, who served in the same battalion as Bergdahl and was among the troops detailed to search for him, wrote in the Daily Beast that troops had been told to keep their mouth shut about what they really thought about Bergdahl's disappearance. Now that he is free, Bethea wrote, the truth can be told: "And that the truth is: Bergdahl was a deserter, and soldiers from his own unit died trying to track him down."

Psaki has said that the deal brokered by the Qatari government included special assurances about the detainees that included banning them from leaving the country for a year and regularly sharing information about them with the United States. Beyond that, Psaki said, "I can't discuss all of the special assurances."

White House Press Secretary Jay Carney, facing sceptical questions about the deal, said the decision was "backed by an ethos that says we don't leave our men and women in uniform behind."

"It was absolutely the right thing to do for the commander in chief, for this administration, to take action to secure his release, the last prisoner of war from the Iraq and Afghanistan wars," Carney said.

While most experts agree that negotiating with terrorist actors such as the Taliban can involve trade-offs to US national security, many differ on the severity of the risk. 

"There is a cost to showing terrorist organizations that there is a benefit to capturing soldiers," said Seth Jones, associate director at the Rand Corporation. "But I actually think US soldiers are pretty threatened in general." 

He emphasised that many countries, including Britain, France, and Israel, negotiate with terrorist groups in order to free them from captivity.

Others point out that while the United States occasionally engages in discourse with terrorist groups, it rarely offers rewards in situations where US hostages are involved. "The US is pretty tough," said Sarah Chayes, a senior associate at the Carnegie Endowment. "Certainly compared to many European countries." In 2004, for instance, the Italian government paid a large sum of money for the release of four of its people who were seized in Fallujah, a move that angered Washington for fear that it would incentivize future kidnappings.

She emphasised that the US government typically favors punishing hostage takers rather than rewarding them. "Not only does the US not typically offer carrots to win the return of hostages, it applies a lot of stick," she said, referring to instances where American citizens or soldiers were kidnapped or taken hostage in Afghanistan, which she has studied extensively. "Every example I saw prompted the focus of tremendous resources on locating the hostage, which led to increased intelligence on militant networks, raids, a lot of people get[ting] killed.... It imposes significant costs on hostage takers." –Foreign Policy