For sheer hypocrisy, it's hard to match the European nations that are refusing responsibility for dozens of their nationals who became jihadist "foreign fighters" over the past five years and are now warehoused in makeshift prisons in northeast Syria.

U.S. officials say that about 2,000 foreign fighters from more than 50 nations are among the roughly 10,000 captured Islamic State fighters held in several dozen ramshackle prisons in Syria. The detention facilities are run by the Syrian Democratic Forces, the Kurdish militia that partnered with a U.S.-led coalition to defeat Islamic State. The other 8,000 captives are Syrian and Iraqi fighters.

The Pentagon and State Department have implored European nations to repatriate their nationals for trial and imprisonment, or at least pay the SDF to hold them temporarily. But so far, most European nations have refused. The SDF warns that it can't imprison them indefinitely and doesn't have laws that would allow formal prosecution in the Kurdish-controlled zone.

"If these prisoners are not going to be taken, what is the endgame?" complained one frustrated Pentagon official in an interview: "What comes next? People haven't thought about it."

The Europeans protest that they don't have adequate laws to try their nationals who committed terrorist offenses on foreign soil, and that they don't have evidence that would stand up in court. They worry, too, that jihadists in European prisons would radicalize other Muslim prisoners, and then be released back into society in a few years, perhaps to commit new terrorist acts.

It's a political problem for Europe, too, explained one European who has talked extensively with officials there about the repatriation issue. "The European Union is in denial," he told me. "The security and interior ministers don't want to hear about it. The Europeans feel that a government that takes them back has no chance for reelection."

The problem isn't just the foreign fighters in the prisons, but their wives and children living in camps. Experts estimate that of the 74,000 people at a huge camp known as Al Hol, about 11,000 may be related to fighters who aren't Syrian or Iraqi.

The European desire for self-protection was epitomized by Ben Wallace, British security minister, who told The Guardian: "I'm not putting at risk British people's lives to go looking for terrorists or former terrorists in a failed state."

The International Committee for the Red Cross, which visits prison and civilian camps in northeast Syria, said in a statement: "Countries of origin cannot turn their backs. People -- especially children -- cannot be made stateless. Faced with this complex problem, moral inertia is not an option."

What peeves some U.S. officials is that the European nations shunning responsibility for Islamic State prisoners have for years been lecturing the United States about its immoral treatment of prisoners at Guantanamo Bay. Facing a post-conflict dilemma now that's similar to what the U.S. encountered with al-Qaida, the Europeans are ducking the problem.

European castigation of Guantanamo abuses included German Chancellor Angela Merkel's statement that "an institution like Guantanamo can and should not exist" and the European Parliament's demand that the U.S. close Guantanamo "without delay." (These criticisms were gathered by the Center for the Study of Human Rights in the Americas.)

President Trump tweeted about the problem on April 30, as the last holdouts of the Islamic State were being routed and sent to the overcrowded, underfunded SDF prisons: "European countries are not helping at all, even though this was very much done for their benefit. They are refusing to take back prisoners from their specific countries. Not good!" For once, Trump was right.

But U.S. pleas have yielded little response, especially from Europe. The only countries to accept significant transfers from the SDF prisons are Kazakhstan, Macedonia, Kosovo, Morocco and Bosnia, a Pentagon official said. Some prisoners have also been transferred to Iraq, which has offered to take thousands more, but only if paid.

The SDF, which has limited resources and faces a Turkish threat of attack, has kept holding the prisoners but warned it can't do so indefinitely. Abdulkerim Umer, an SDF representative, told The Associated Press: "We can't put up with this burden alone. ... The international community has evaded its responsibility, so we ask that they help us set up the court here."

European nations talk of some sort of international tribunal for the jihadist prisoners, but there's been no significant movement to make that happen.

Defeating the Islamic State was a worthy goal. Ignoring the prisoners who were captured in that war, and leaving the problem to others, is reprehensible.

— Follow David Ignatius on Twitter: @IgnatiusPost. David Ignatius writes a twice-a-week foreign affairs column.