Police in the city of Nelson detained Kyle Snyder, 23, on Friday on a detention order issued by the Canadian Border Services Agency.
"We felt he might be inadmissible to Canada," said agency spokeswoman Janis Fergusson. "He was interviewed and released."
Snyder, of Colorado Springs, Colorado, a former combat engineer, originally went absent from the Army and fled to Canada in April 2005 while on leave, the AP says.
He returned to the military last November but fled again almost immediately. At the time, Snyder's attorney, James Fennerty of Chicago, said the Army wanted to send Snyder back to his original unit at Fort Leonard Wood, Missouri, where commanders would determine his future.
A phone call to an official at Fort Leonard Wood was not immediately returned.
The Chinese military believe that Beijing and Moscow must resist pressure from Washington together