Neo-Nazis and white supremacists from the United States and Europe have traveled to Ukraine to fight on both sides of the war with Russia, providing these extremists with valuable battlefield experience as they seek to increase their violent operations domestically, according to a report from a watchdog group monitoring the situation.

Foreign fighters from at least 35 neo-Nazi, white supremacist, and ultranationalist groups based in the United States, Canada, and Europe “have members fighting on both sides in [the] Russia-Ukraine conflict,” according to an analysis from the Middle East Media Research Institute (MEMRI), which has been tracking the flow of extremist groups into the region.

The groups are seeking to give their allies “combat experience, saying that the training and materials given to volunteers who travel to Ukraine will be useful in a future civil war in their home countries.” Americans who have joined the conflict include residents of Texas, Ohio, Virginia, and Tennessee, according to the report.