Geography of Oman around the Al Hajar mountains are part of the Gulf of Oman desert and semi-desert ecoregion, while the mountains themselves are a distinct habitat. The northernmost area, Musandam, extends from the tip of the Musandam Peninsula to the boundary with the United Arab Emirates (UAE) at Hisn al Diba. It borders the Strait of Hormuz, which links the Persian Gulf with the Gulf of Oman, and is separated from the rest of the sultanate by a strip of territory belonging to the UAE. This area consists of low mountains forming the northernmost extremity of the Al Hajar al Gharbi (Western
Persian Gulf naming dispute as the Arabian Gulf". Since about 2009, due to increased cooperation with Arab states of the Persian Gulf, various branches of the United States armed forces have issued directives to their members to use the "Arabian Gulf" when operating in the area to follow local conventions ("Persian Gulf" is still used in official publications and websites). The practice of the United States Fifth Fleet, based in Bahrain, is to use "Arabian Gulf": The National Geographic Society uses the name Persian Gulf to refer to this body of water. In 2004, the society published a new edition of its "National Geographic