US officials are concerned that American white supremacists that have been traveling to Ukraine to fight alongside the neo-Nazi Azov Battalion and similar units may eventually become a domestic threat when they return home, said a US intelligence report obtained and reported on by Politico on Friday.

The US Customs and Border Protection (CPB) posted the intelligence bulletin on March 7, and as per the report, concerns arose in Washington about two weeks after the start of the Ukraine war.

According to the documents, US citizens, including former service members, would leave for Ukraine to fight alongside the International Legion of Territorial Defense of Ukraine.

Officers from the CBP interrogated five US nationals at the John F. Kennedy International Airport and searched the luggage of a sixth, all of which had been heading to Ukraine, the document said, as quoted by the report.

Washington bans US citizens from joining foreign armies under the US Neutrality Act dating back to George Washington's presidency.

The report, however, revealed that the federal government had not pressed criminal charges against citizens who went and fought for Kiev despite law enforcement officers having many opportunities to bring charges over their actions.

US National Consortium for the Study of Terrorism and Responses to Terrorism co-founder Arie Kurglanksi told Sputnik this development was troubling because of the consequences it could have in the United States.

"This is a troubling development for two reasons: one is that far-right volunteers returning from the Ukraine war would have the aura of war heroes, in addition to military experience, and could augment the radicalization of others for whom they would serve as role models," Kruglanksi said.

"We know from the Mujahadeen war against the Soviets in Afghanistan that those returning fighters were a major factor in galvanizing others to join Al-Qaeda, for instance, in Indonesia, the Philippines, and Malaysia, among others, as well as contributing to the formation of ISIS in Iraq," he added.

The US intelligence bulletin, according to Kruglanksi, legitimizes Russia's argument that it is fighting neo-Nazis in Ukraine, which would curb the West's efforts at demonizing Moscow and the goals of its operation.

"The neo-Nazis have been a big issue in the US and in Europe to an increasing degree," he said. "You see [them] in countries like Germany, like France, like Poland, like Hungary. These far-right movements have been gaining ascendance. In this country [United States] as well."

Washington, since the start of the Ukraine war, has been the largest contributor of military equipment to Ukraine, which has received tons of equipment from about 14 countries.

Among a wide array of military equipment supplied to Kiev, there are more than 1,400 stinger SAM systems, 5,500 Javelin anti-armor systems, Switchblade drones, and M777 155mm howitzers.

US President Joe Biden authorized an additional $100 million in military aid for Ukraine, using his presidential drawdown authority for the 10th time, which will see Kiev obtaining an additional 18 M777 howitzers and three AN/TPQ-36 radar systems, among other pieces of equipment.

Following reports about the West granting more arms to Ukraine, The Washington Post reported Moscow sent a formal diplomatic note to the United States warning that Washington and Brussels' arms shipments were adding fuel to the fire of the war in Ukraine, stressing that this matter could bring upon "unpredictable consequences".

The US is still sending arms to Ukraine despite the Russian ambassador to the US, Anatoly Antonov, warning that the influx of Western arms to the conflict zone in Ukraine was adding fuel to the fire.