Millions of people around the world view a U.S. passport as a ticket to freedom and opportunity; for journalists in war zones, however, that passport can be the equivalent of a death warrant.

The fate of Steven Sotloff and James Foley in recent weeks sent a grim reminder that American journalists who fall into the hands of certain radical groups have a higher probability of being killed, because the U.S. government refuses, as a matter of policy, to pay ransoms to secure the release of citizens held hostage. European hostages held by Foley’s and Sotloff's captors were released after ransoms were allegedly paid.

The statements that Foley and Sotloff were forced to read before their murders also underscored the propaganda value of U.S. hostages, whose killing can be used to send a message to the world. Europeans, on the other hand, are more likely to bring in millions of dollars.

David Rohde, a former New York Times journalist held captive for seven months by the Taliban in Afghanistan and Pakistan five years ago, argued recently that the difference between European and U.S. policies on paying ransoms has failed to “deter captors or [to] consistently safeguard victims.”

European governments publicly deny ever paying for the release of hostages, but a recent New York Times investigation found that Al-Qaeda affiliates “have taken in at least $125 million in revenue from kidnappings since 2008, of which $66 million was paid just last year.”

Rohde said his editors, his family and the U.S. administration declined to pay the millions demanded by his captors. But he revealed that Foley expected a different response. “Foley believed that his government would help him, according to his family,” Rohde wrote. “In a message that was not made public, Foley said that he believed so strongly that Washington would help that he refused to allow his fellow American captives to not believe in their government.”

Foley’s family hadn’t heard from him in more than a year after he was taken. It was 16 months into his captivity that they learned where he was, only because two Spanish journalists who had been held with him were freed after a ransom had been paid.

“Simply put, kidnapping for ransom has become today’s most significant source of terrorist financing because it has proven itself a frighteningly successful tactic,” said David S. Cohen, undersecretary for terrorism and financial intelligence at the Treasury Department, speaking in London in 2012. “Any payment of ransom provides an incentive for further kidnapping operations. Each transaction encourages another transaction.” He urged U.S. allies to stop paying ransoms in order to remove that incentive for kidnappings.

Former U.S. diplomat Vicki Huddleston was even more forthright in remarks to The New York Times, saying, “The Europeans have a lot to answer for. It’s a completely two-faced policy. They pay ransoms and then deny any was paid.”

But the practice doesn’t appear to have stopped. Global intelligence firm Stratfor wrote in May this year that the Islamic State fighters had set themselves apart from other rebel groups in the region by kidnapping foreigners for ransom. On April 19, it reported, Turkish soldiers found four French journalists bound and blindfolded on the border with Syria, set free after nearly eight months of captivity at the hands of the IS. “Although French Foreign Affairs Minister Laurent Fabius has insisted that the French government does not pay ransoms, it has been reported that $18 million was paid to secure the journalists’ release,” the report said.