Abu Musa and the Greater and Lesser Tunbs conflict

On 30 November 1971, when British forces withdrew from the islands of Abu Musa, Greater Tunb and Lesser Tunb in the Strait of Hormuz, Iranian marines moved in to take back territorial control of the islands after British occupation.

Causes
The Tunbs were in the dominions of the kings of Hormuz from 1330 until 1507 when they were invaded by Portugal. The Portuguese occupied the island until 1622, when they were expelled by Shah Abbas. The islands were occupied by the British Empire on 7 June 1921, and they were put under administration of the Emirate of Sharjah. In 1971, shortly before the end of the British protectorate and the formation of the United Arab Emirates, Iran assumed partial control of Abu Musa under an agreement of joint administration together with Sharjah. A day later on 30 November 1971, Iran seized the Islands and took control over them.

Operation
On 30 November 1971 the Imperial Iranian Navy seized the islands under small resistance of the tiny Arab police force stationed in there. Despite the agreement between Sharjah and Iran, Ras Khaima ruler resisted the Iranian troops that were sent to the Tunbs. The Iranians planes kept shooting the police station which made the Arab forces to return fire on ground troops. According to some sources, the Arab civilian population of Greater Tunb was then deported, but according to others the island had already been uninhabited for some time earlier.

Aftermath
In the following decades, the issue remained a source of friction between the Arab states and Iran. Negotiations between the UAE and Iran in 1992 failed. The UAE have attempted to bring the dispute before the International Court of Justice, but Iran refused. Tehran says the islands always belonged to it as it had never renounced possession of the islands, and that they are part of Iranian territory. The United Arab Emirates argue that the islands were under the control of Qasimi sheikhs throughout the nineteenth century, whose rights were then inherited by the UAE after 1971. Iran counters by stating that the local Qasimi rulers during a crucial part of the nineteenth century were actually based on the Iranian, not the Arab, coast, and had thus become Persian subjects. In 1980, the UAE took its claim to the United Nations, but it was rejected by the UN Security Council, and the case was closed.