Fears of vulnerability were realised the day before independence. An Iranian destroyer group broke formation from an exercise in the lower Gulf, sailing to the Tunb islands. The islands were taken by force, civilians and Arab defenders alike allowed to flee. A British warship stood idle during the course of the invasion. A destroyer group approached the island Abu Musa as well. But there, Sheikh Khalid bin Mohammed Al Qasimi had already negotiated with the Iranian Shah, and the island was quickly leased to Iran for $3 million a year. Meanwhile, Saudi Arabia laid claim to swathes of Abu Dhabi.