An Iraqi security source said on Friday that the two US companies Lockheed Martin Corp and Sallyport Global, prepared a plan to evacuate their staff from Balad air base, depending on the development of the security situation. The two companies told their local Iraqi workers that they will inform them about the companies' final evacuation decision within 10 days. Hundreds of U.S. contractors are working with the two companies to provide support and advice for the Iraqi airforce after Iraq purchased F-16 jet fighters from the United States. The latest decision came amid rising tensions in the Middle East between the United States and Iran, particularly after the Iranian air defense system shot down an RQ-4A Global Hawk unmanned aircraft on June 20.