It’s not just average, everyday Ukrainians who are picking up rifles and defending their nation. After Ukrainian president  Volodymyr Zelensky announced the formation of an international legion of fighters, several thousand U.S. citizens have answered the call and have volunteered their services.

According to the Ukrainian embassy in Washington, D.C., about 3,000 Americans, many of them veterans, have contacted the embassy looking for a way to lend a hand in their fight for independence.

When Matthew Parker, an American veteran with 22 years of service in the U.S. Army, heard that Russian forces had invaded Ukraine, he thought about a Ukrainian American soldier who had served alongside him with U.S. forces in Iraq and decided he wanted to help the Ukrainians defend their homeland.

“I had a soldier in Iraq with me who was from Ukraine,” he told VOA of his decision to join what he sees as a fight about justice and friendship. “He became an American citizen, joined the Army, and he told me about his home. He told me about his family and how proud they were. I remember him telling me about his little sister.

“Now … I’d like to think that by going to Ukraine, maybe I protect his mother, or his little sister or his home. Maybe in some small way, I say thank you to him for serving by doing something like this.”

Parker told Voice of America that he and twelve other veterans had already committed themselves to helping defend Ukraine before Zelensky called for the establishment of an international battalion comprised of 16,000 foreign volunteers. The original plan was to fly to Poland before making their way overland into Ukraine where they could sign up with the Territorial Defense Forces, but the veteran says now that the international legion is taking shape, he and his fellow volunteers believe they can be more effective fighters.

“When we did not have the procedure, it would have been a process of showing up at the border. Maybe not knowing how to speak the language and trying to convince somebody. This way, they know our experience. They know our training. They can send us to places where they need us,” he said.

Parker, a native of the U.S. state of South Carolina, said in his years with the U.S. Army, he had been an instructor as well as a combat leader who led soldiers in combat situations.

“They can place me where they need me,” he said. “Or they can only leave me as an instructor with the legion to teach Ukrainians how to use different weapons systems. So now they have a choice, they can put me in combat or use me as an instructor, but we’re happy to help in whatever.”

According to Ukraine’s foreign minister, nearly 20,000 people from across the globe have now volunteered to serve, and fighters have been trickling into the country over the past several days. But Ukraine’s adversary is also reportedly recruiting foreign fighters as well, with the Wall Street Journal reporting on Monday that Russian president Vladimir Putin has put out the call for Syrian fighters to operate as “guards” in portions of Ukraine occupied by Russian forces.

An American assessment indicates that Russia, which has been operating inside Syria since 2015, has in recent days been recruiting fighters from there, hoping their expertise in urban combat can help take Kyiv and deal a devastating blow to the Ukraine government, according to four American officials. The move points to a potential escalation of fighting in Ukraine, experts said.

It is unclear how many fighters have been identified, but some are already in Russia preparing to enter the conflict, according to one official.

Officials declined to elaborate on what else is known about the deployment of Syrian fighters to Ukraine, the status or precise scale of the effort.

According to a publication based in Deir Ezzor, Syria, Russia has offered volunteers from the country between $200 and $300 “to go to Ukraine and operate as guards” for six months at a time.

There’s no official word on how many Syrian recruits the Russians have managed to muster, but I’d recommend that any Syrians heading to Russia to help them occupy Ukraine first get a written guarantee from Putin’s government that if and when they’re killed, their bodies will be shipped home to their families instead of being left to be used as fertilizer for sunflowers, as has been the case for many of the Russian soldiers who’ve been killed in the invasion.

The Ukrainians have already shown their unconquerable spirit in the first twelve days of the invasion, and the thousands of reinforcements headed their way should help them stay in the fight in the dangerous days ahead. Godspeed to Matthew Parker and the thousands of other Americans who are volunteering to stand with the Ukrainian people in the nightmare that they’re living through, and I hope that they’re able to swiftly and safely return home to the families and friends they’re leaving behind.