Iran began a massive seven-day air defense exercise in the eastern regions of the country, semi-official Fars News Agency reported on Monday.

The exercise, which involves joint maneuvers between the major branches of the Iranian armed forces, including the air force, army, navy, border patrol and the Islamic Revolutionary Guards, is to take place over some 850,000 square kilometers.

Khatam al-Anbia Air Defense Base General Shahrokh Shahram told Fars that the exercise is intended to practice “defending hypothetical sensitive sites.”

Fars reported that “in addition to testing mobility and rapid reaction capability of participating units, the air defense units will test artillery and missile systems’ capabilities for confronting different types of Unmanned Aerial Vehicles (UAVs) flying in different altitudes.”

On November 1, the Iranian air force fired on a US Predator drone which the US maintains was over international waters near Iranian territory. The drone was not hit.

Israel has repeatedly urged the international community to set “red lines” on Iran’s nuclear development, with a military attack on the table as a measure of last resort in case it refuses to halt its nuclear drive.