shortest thesis sentence: A dramatic, dayslong incursion into Russian territory has fueled questions about the NAME_1’s defenses but also about whether Ukraine may be going to new lengths in its efforts to penetrate them. The Belgorod border raid has thrust two groups of largely unknown fighters with neo-Nazi ties into the heart of the conflict. Russia has blamed the attack on Kyiv, but Ukraine has denied any involvement. As the chaos and confusion subsides, the two militant groups have emerged from relative obscurity to claim responsibility, taunt the NAME_1 and promise more to come. NBC News looks at who and what appears to be behind the raid. Two groups claiming to be Russians fighting on behalf of Ukraine say they carried out the attack. Both describe themselves as Russian dissidents and have members who espoused white nationalist views. The Russian Volunteer Corps, or RVC, says it’s made up of Russians fighting on Ukraine’s side and against Putin's government. The group made headlines in March when it claimed to be behind a smaller raid in the Bryansk region. Its commander, NAME_2, who also goes by the last name of NAME_3, is a white nationalist and ex-soccer hooligan who shares neo-Nazi views. NAME_4 is listed on Russia’s federal wanted list and its register of extremists and terrorists. The U.S.-based Anti-Defamation League has described NAME_4 as “a Russian neo-Nazi who lived in Germany for many years.” He goes by the call sign “White Rex” and reportedly founded a clothing brand of the same name that is popular among Russian neo-Nazis. The RVC’s channel on the Telegram messaging app has more than 110,000 followers and has shared photos of what it says are the group’s fighters on the war's front lines. Some of their posts have anti-immigration and pro-white European rhetoric. In a post on Tuesday, the group clarified that it “adheres to right-wing conservative political views and traditionalist beliefs.” The group says that it consists of mostly volunteers, ethnic Russians and Russian citizens living in Ukraine, who have fought for Kyiv since 2014. The Freedom of Russia Legion is the other group that claims to have been involved, and also portrays itself as Russians who are fighting for Ukraine and against Putin. The legion says on its website that it was formed last spring “out of the wish of the Russians themselves to fight against Putin’s armed gang in the ranks of the Armed Forces of Ukraine.” Please answer in JSON format.
user