By 16 July, the Iranians had in their first attack succeeded in overrunning the forward Iraqi defence lines right at the border, gained in their deepest penetration 16 km (9.9 mi) inside Iraq and claimed to have captured 288 square kilometers (180 square miles) of Iraqi territory albeit with a great deal of casualties. The Iranian forces had penetrated as far as the Kutayba river, a tributary to the Shatt Al Arab river, but failed to cross it. However, the Iranian forces came to a halt as the Iraqis stopped the main Iranian attack and launched frontal and flanking counter-attacks supported by air strikes from fighter-bombers that pushed the Iranians back to within 4 kilometers (2,5 miles) from the border.