Of Iraq's six divisions that invaded by ground, four were sent to Khuzestan, which was located near the border's southern end, to cut off the Shatt al-Arab from the rest of Iran and to establish a territorial security zone. The other two divisions invaded across the northern and central part of the border to prevent an Iranian counter-attack. Two of the four Iraqi divisions, one mechanised and one armoured, operated near the southern end and began a siege of the strategically important port cities of Abadan and Khorramshahr.