Putin forces sent Ukrainian children to brainwashing camps

The Putin forces sent thousands of Ukrainian children (at least 6000) to brainwashing camps to inculcate Russian identity and loyalty to Russia.

Some of them left with their parents' permission. Others were given no other way to leave the battlefield. Some were cut off from all further contact with their families. Some never came back.

I cannot tell whether this literally includes only children, or minors of all ages up to 18.