Islamic Republic of Iran Navy
It is charged with the responsibility of forming Iran's first line of defense in the Gulf of Oman and beyond with the mission of acting as an effective blue-water navy. However, it is generally considered as a conventional green-water navy as it mostly operates at a regional level, in the Persian Gulf and Gulf of Oman but also as far afield as the Red Sea, the Mediterranean Sea and northwest quarter of the Indian Ocean. In July 2016, the Navy said that it would establish a presence in the Atlantic Ocean, of unspecified duration.
Iran–Iraq relations
The 1937 treaty recognised the Iran–Iraq border to be along the low-water mark on the Shatt al-Arab's eastern side, except at Abadan and Khorramshahr, where the frontier ran along the thalweg (deepest part of the river valley). This gave Iraq control of most of the waterway and required Iran to pay tolls whenever its ships used it.