A new video appears to the show Syrian rebels showing off a rather unusual bit of weaponry: A World War II-era German howitzer.

In the video, which was released by Shaam News Network, members of the Islamic Front are shown loading and firing what appears to be a 10.5 cm leFH 18, a 105 mm light howitzer that entered service with Nazi Germany's armed forces in 1935.

According to German newspaper BILD, the video is the first evidence that the leFH 18 is in use in Syria, and it's unclear how the rebels have acquired it. Some experts weren't surprised, however. "The Syrian Army was known to operate limited numbers of the 10,5 cm leFH 18M howitzer, as well as the 7,5cm PaK 40 anti-tank gun. It is likely that the howitzer shown was captured from a Syrian Army base or museum," N.R. Jenzen-Jones, the Director of Armament Research Services (ARES), explains.

This isn't the first time World War II-era weapons have been used in Syria's conflict, which began in 2011. In August 2012, rebel group Al-Tawhid Brigade released a video that appeared to show a large number of StG 44s in their possession. These guns were produced by Nazi Germany during World War II and are considered the first modern assault rifle.

A number of other weapons from the World War II period have been put to use in Syria, and rebel groups have been found to use improvised weapons like pipe bombs and catapults.

"In times of internal civil conflict, it is not uncommon to document legacy arms and munitions in the hands of combatants, especially combatants with limited access to more modern systems," Jones said.

The Islamic Front, not to be confused with the rival group the Islamic State, are one of a number of groups battling for control in Syria. More than 200,000 people are believed to have died in the conflict so far.

See also:

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Update: This story has been updated with further comment from N.R. Jenzen-Jones.