The farther a howitzer is away from its intended target the less accurate standard shells become. This is called the circular error probable or CEP. This means at around 18 miles (the maximum range of a standard 155mm artillery shell fired from a M777A2 howitzer), half the rounds fired could land within an 853-foot circle around the target. The XM1156 reduces that circle to just shy of 100 feet, according to Army documents.
The XM1156 appears to have first popped up in Afghanistan in 2013, and in 2015, according to a report from Defense News, Orbital ATK was awarded a $120 million contract by the U.S. Army for the guidance kits. Canada and Australia has also experimented with them.
The U.S. military also fields other types of guided artillery shells, the XM982 GPS-guided Excalibur. The Excalibur increases the range of the M777A2 to roughly 25 miles.
The Marine artillery unit, though unnamed in the video, probably came from the 24th Marine Expeditionary Unit. The howitzer battery is providing fire support — along with guided rocket artillery — to U.S.-backed Syrian fighters battling the Islamic State in their de-facto capital of Raqqa. Open-source imagery has geo-located the Marine artillery within 10 miles of Raqqa, meaning even the unguided shells fired from the unit’s howitzers will land somewhat accurately —depending on weather.
Though the XM1156 is meant to reduce civilian deaths and unnecessary damage to civilian structures, the U.S. military has been accused of causing hundreds of civilian casualties in Raqqa in recent weeks. Last month, videos appeared online of what looked M825-series white phosphorus smoke shells bursting over the Syrian city, setting some structures ablaze. Those type of shells appeared in the recent video posted online and have also been documented in prior images circulated by the Pentagon.