There are few acts in which President Trump takes as much visible pride as freeing U.S. citizens held by foreign nations.

Soon after taking office, Trump helped secure the release of Aya Hijazi, an Egyptian American charity worker who had been imprisoned in Cairo for nearly three years. His administration has since overseen the release of several American citizens who were held by North Korea and helped in complex negotiations that freed Americans held in Turkey, China, Venezuela and other countries.

Trump has portrayed such rescues as a particular mission for his presidency. “We’ve had 17 [jailed Americans] released, and we’re very proud of that record,” Trump said in May 2018 after the release of Josh Holt, a U.S. citizen held in Venezuela for two years. “Very proud. And we have others coming.”

Some former prisoners have praised Trump for taking a personal interest in their plight. “From the time you took office, we know that you’ve been engaged,” American pastor Andrew Brunson, who was freed from Turkish prison in October, said to Trump when they met in the Oval Office.

But what will happen now that an American is being held by a nation with which Trump has a deeply ambiguous relationship?

Russia’s domestic security service announced Monday it detained an American citizen in Moscow on Dec. 28, under suspicion of espionage. The American is 48-year-old Paul Whelan, whose family has said he was merely visiting Russia for a wedding.

U.S. intelligence experts have expressed doubt that Whelan, who was discharged from the Marines for bad conduct and now works in corporate security, would have been involved in official U.S. espionage. Whelan’s arrest came shortly after Maria Butina, a Russian gun-rights activist, pleaded guilty to conspiring to infiltrate U.S. conservative groups for the Kremlin.

“The Russians are saying we’re pissed with the United States,” said Bill Richardson, a former U.S. ambassador to the United Nations who has taken part in a number of hostage negotiations.

Richardson, who now leads a nonprofit prisoner-release group, said Moscow was probably seeking a “quid pro quo” agreement; he said he is trying to arrange a meeting with the Russian ambassador to the United States in a bid to help Whelan.

Trump’s reaction to the case will be scrutinized closely. Although his administration has been tough on what it sees as Moscow’s acts of aggression, and it has imposed sanctions on Russian officials, the U.S. president himself has sought to maintain cordial relations with Russian President Vladimir Putin and has refrained from criticizing him.

Secretary of State Mike Pompeo said Wednesday if Whelan’s detention is found not appropriate, “we will demand his immediate return.” A State Department official, speaking on the condition of anonymity because of department guidelines, said U.S. ambassador to Russia Jon Huntsman Jr. visited Whelan on Wednesday at a detention facility in Moscow. But Trump has yet to publicly mention Whelan’s fate.

The State Department also has a special presidential envoy for hostage affairs, Robert O’Brien, who was appointed last May. A State Department official would not say whether O’Brien was helping with Whelan’s detention, citing privacy concerns.

Earlier this year, O’Brien said about 20 Americans were being held unjustly around the world, and he called on both Russia and Iran to use their influence to help free one particular U.S. citizen: Austin Tice, a freelance journalist who was captured in Syria six years ago.

Tice’s uncertain fate shows U.S. influence cannot always get Americans home. Indeed, despite Trump’s 2016 pledge and his focus on the detainees being held in Iran, Washington has made little headway in securing the release of a number of American citizens imprisoned in the Islamic republic.

Richardson said in Whelan’s case, Trump’s personal involvement may in fact hurt the American’s chances of being released. Instead, he argued, negotiations should be kept low profile.

“The president should stay thoroughly out of it,” Richardson said, but “he probably won’t. He can’t resist.”

Correction: This article has been updated to remove an incorrect reference to Robert O’Brien working under the Obama administration. A different man, James O’Brien, had worked under the Obama administration as special presidential envoy for hostage affairs.

Read more: