The “mastermind” of the November 13 Paris attacks, Abdelhamid Abaaoud, was radicalized in a Belgian prison while serving time for theft. Charlie Hebdo and kosher supermarket shooters Amedy Coulibaly and Cherif Kouachi also spent time in jail, meeting in a French prison in 2005, where they were radicalized to violent Islamism by a fellow inmate.

The threat of prison radicalization—especially severe in France and Belgium—may feel remote to Americans, but it shouldn’t. During the past two years, dozens of homegrown jihadists have begun to trickle into our prisons, convicted of providing material support to ISIS and other extremist groups. As the Obama administration promotes criminal justice reform and outlines initiatives, we’d do well to include counter-extremism programs in any prison reform package. It would be money well spent.

While Europe’s prison radicalization problem is well known, the potential for radicalization in the U.S. has not always been appreciated, except by extremists. In the past, al-Qaeda manuals have specifically identified American inmates as targets for conversion, pointing to their existing disillusionment with U.S. policies. Today, at least seven Americans convicted on ISIS-related offences had already served time in U.S. prisons, often on unrelated charges like drug possession.  While in prison, terror convicts—like attempted al-Shabab fighter Zachary Chesser—have managed to engage in unauthorized meet-ups with other convicted terrorists, raising the fear that radicalization may already be taking root.

As a result of recidivism and jihadist attacks, some countries, like France and Belgium, have awoken to the perpetuation of terror through prison radicalization. These governments have begun to isolate dangerous jihadists from the larger prison population, and are now hiring expert Muslim staff in an attempt to reeducate radicalized inmates. In Saudi Arabia, a major de-radicalization program—boasting a 90% success rate—consists of intense religious debate and psychological counseling within prisons. While these programs lack robust longitudinal data, they mark crucial first steps in tackling a dangerous pattern worldwide.

Unfortunately, the U.S. has yet to implement any de-radicalization programs in its own prison system, although there have been some U.S. efforts to explore de-radicalization in detention centers in Iraq and Afghanistan. In Minnesota recently, one judge experimented with a de-radicalization program for an ISIS-inspired teen, but the program came to an abrupt end in April after a box-cutter was discovered under his bed. There are no known plans to expand or replicate the experiment.

Despite the disappointment of the Minnesota intervention experiment, we cannot afford to give up on de-radicalization. We need a tailed approach for prisons designed to both rehabilitate those who enter the prison system already radicalized, as well as to prevent indoctrination of the larger prison population. De-radicalization programs must be subject to detailed examination and rigorous, independent evaluation. But nascent American programs can draw from the seemingly successful characteristics of existing programs worldwide: pro-social and pro-Western education, vocational training, family engagement, and an emphasis on individualized attention.

Fortunately, some of the prison reforms President Obama promoted in July—reduced overcrowding, a crackdown on gang activity, and vocational training—may have the corollary benefit of reducing the threat from emerging jihadist networks. It’s a first step, but more is needed. By addressing this threat now, we can prevent U.S. correctional facilities from becoming factories for jihadism.