(NewsNation) — The mother of Alex Drueke, one of the military veterans who have gone missing while fighting with a Ukrainian Army unit, said she hasn’t heard from her son in more than a week.

Lois Drueke said she and Alex kept in close contact after he first left in April. He wanted to go help train Ukrainian forces, she said.

“He’s a very strong, brave, loyal American,” she said.

Alex joined the army after 9/11, and completed two tours in Iraq.

When Russia invaded Ukraine in February, Alex told Lois he wanted to use his experience to help others.

The fates of Alex and Andy Tai Ngoc Huynh, 27, of Trinity, Alabama, the other veteran who went missing, are unknown. Their relatives have been in contact with the state’s congressional delegation.

On June 8, Alex sent Lois a message, warning her he was going to “go dark” for a day or possibly two. She wrote back urging him to “stay safe. I love you.”

Since then, no one has heard from either Alex or Hyunh. The unit they served in posted a message saying they become isolated in Kharkiv last week before a Russin offensive allegedly led to both men being captured.

The State Department remained tight-lipped about the status of the two veterans Thursday, with spokesman Ned Price saying they are limited in what they can say.

But the State Department did say the two men should be treated as prisoners of war if the Russians captured them.

“Any person detained by Russia in connection with the conflict must be afforded fundamental guarantees including humane treatment and fair trial rights,” Price said.

For now, their families hope for updates soon, as they pray the two men remain alive and safe.

The State Department warned again Thursday of the dangers of Americans traveling overseas to help in Ukraine, saying the warzone conditions put many lives in jeopardy.