Satellite images have picked up images of a previously unknown ground-to-ground missile manufacturing plant in Syria. It has raised new concerns in Israel about the extent of military cooperation between the two countries.

The photographs were taken by ImageSat International, an international company based in Cyprus and Israel. The images show an installation on the outskirts of Wadi Jahannam in northwestern Syria that bears a striking resemblance to Parchin’s installation in Iran, which has been linked to missile development under the Islamic Republic’s nuclear program.

The report identifies the site as a missile factory without providing further details, but suggests a sudden apparent increase in construction work on the site.

The report also states that unlike other facilities in Syria that have been attacked by the Israeli Air Force, this will be difficult to bomb because of its proximity to a Russian battery of S-400 anti-aircraft missiles, considered one of the most advanced defense systems in the world.