Doha, Qatar - US military bases continue to form a strategic envelope around Iran, although the American withdrawal from Iraq at the end of 2011 may have changed the regional balance somewhat towards Iran's favour. While US forces are scaling back in many parts of the globe due to budget cuts - and have begun a gradual depature from Afghanistan to be completed by 2014 - their international presence remains vast.

From an active-duty force of 1.4 million soldiers, the US has deployed some 350,000 troops to at least 130 foreign countries around the world. Some are at Cold War-era installations, but many are in or near combat zones in the Middle East. At more than 750 bases internationally, private contractors and third-country nationals also form a large percentage of the staff, in addition to military reservists and civilian employees of the Pentagon.

US military installations in the Middle East serve to keep an eye on Iran, but their regional footprint was significantly expanded well before Iran became the most publicly cited foreign "threat".