Operation Nasr-4 was a successful Iranian offensive in Iraqi Kurdistan.
After Operation Karbala 5 the southern front (Basra) had come to a complete halt, while Iran was losing in the central front. The only place Iran could still rely on to win the war was the North. In May, Iran launched Operation Karbala Ten, in this operation Iran supported by Kurdish Peshmerga defeated Iraq and endangered Kirkuk.
After coming dangerously near the city of Kirkuk with Karbala-10, Iran launched Operation Nasr-4 which became one of Iran's greatest successes in the war. Supported by the Kurds, Iranian Pasdaran fighters under the command of the brilliant Lieutenant General Ali Sayad Shirazi attacked Iraq.
Nothing more happened in the south until Iraq reinvaded the Al-Faw Peninsula front while Iraq recaptured almost all land lost in the central front (with use of gas). Iraq could attack Iranian oil platforms and oil tankers while Iraq has their loads transported via other Arab countries, Iran got frustrated and started attacking neutral ships, this ended in the US starting Operation Earnest Will to protect the ships, Iran kept on attacking and, after a US ship was heavily damaged by an Iranian mine the US launched Operation Praying Mantis. In this operation they first damaged 2 Iranian oil-platforms, followed by the largest naval battle since World War II. The Iranian navy lost a frigate, a gunboat and several speedboats during the battle. In the north Iran continued advancing and Saddam started gassing the Kurdish population. Following this Ayatollah Khomeini finally accepted peace. But by this time Saddam didn't want peace anymore and attacked Iran for Kermanshah but Iran halted his attack and in the south the People's Mujahedin of Iran which attacked Khuzestan with Iraqi air support where defeated and their army was completely destroyed in Operation Mersad. Now Saddam also accepted peace and the 8 year war was finally over.