The incident occurred south of the city of Palmyra.
Since dictator Bashar al-Assad was ousted from power in Syria at the beginning of December, the observatory has registered six IS attacks in the Syrian desert. Around 20 civilians have been killed and more than 50 Assad soldiers have abandoned their posts.
In 2014, IS took over large parts of Syria and Iraq and proclaimed a "caliphate" and launched a reign of terror.
Despite losing its last area in Syria in 2019, remaining members still carry out deadly attacks, particularly in the desert stretching from the outskirts of Damascus all the way to the Iraqi border.
Most of IS's attacks in recent years have targeted Kurdish-led fighters or loyalists to the now-deposed President Bashar al-Assad's government.
Since Assad was ousted, among others, US Secretary of State Antony Blinken has emphasized the importance of working to prevent the terrorist sect from gaining new footholds in the region.
