Jordan's security forces say the military has arrested four unarmed Syrian soldiers found in the zone between the two countries' borders.
A security spokesman said the men were arrested on Monday and are being interrogated. He spoke on condition of anonymity because he is not permitted to make press statements
It was unclear whether the soldiers were trying to enter Jordan or were attempting to return to Syria.
The security spokesman could not provide further details as the probe is underway.
More than 1,000 senior Syrian army and police officers have defected to Jordan during the 21-month conflict.