This seems to be more symbolically focused, as there are only 2 Jets staying for a week. Nevertheless, it is important to note.The US Air Force and the Bulgarian Air Force will jointly conduct air policing to protect Bulgarian airspace starting on 9 September 2016. Two US F-15 fighter jets will join Bulgaria’s MIG-29s for a week on this mission, which is part of NATO’s enhanced air policing measures for eastern Allies.
Until now, air policing over Bulgaria has been conducted by national means. The enhanced air policing measures for Bulgaria are being launched by NATO for the first time, in response to a request by the Bulgarian authorities.
Air policing scrambles respond to military and civilian aircraft that do not follow international flight regulations, or approach NATO airspace without proper clearance. Often they fail to properly identify themselves, communicate with Air Traffic Control, or file flight plans. NATO’s air policing responses seek to minimise risks, and ensure the safety of the airspace and its users.
NATO air policing helps ensure equal protection for all Allies, including those who do not have the full range of air defence assets in their own militaries.
Source: http://www.nato.int/cps/en/natohq/news_ ... medium=smc