Past no-fly zones
In 1991, the United States, United Kingdom, France, Turkey, and other states intervened in Kurdish-Iraqi dispute in northern Iraq by establishing a no-fly zone in which Iraqi aircraft were prevented from flying. The intent of the no-fly zone was to prevent possible bombing and chemical attacks against the Kurdish people by the Iraqi regime of Saddam Hussein. The initial operations were dubbed Operation Provide Comfort and Operation Provide Comfort II and were followed by Operation Northern Watch. While the enforcing powers had cited United Nations Security Council Resolution 688 as authorizing the operations, the resolution contains no explicit authorization. The Secretary-General of the UN at the time the resolution was passed, Boutros Boutros-Ghali called the no-fly zones "illegal" in a February 2003 interview with John Pilger. In southern Iraq, Operation Southern Watch was established in 1992 to protect Iraq's Shia population. It originally extended to the 32nd parallel but was extended to the 33rd parallel in 1996.
Bosnia and Herzegovina, 1993–1995
In 1992, the United Nations Security Council passed United Nations Security Council Resolution 781, prohibiting unauthorized military flights in Bosnian airspace. This led to Operation Sky Monitor, where NATO monitored violations of the no-fly zone but did not take action against violators of the resolution. In response to 500 documented violations by 1993, including one combat violation, the Security Council passed Resolution 816, which prohibited all unauthorized flights and allowed all UN member states to "take all necessary measures...to ensure compliance with [the no-fly zone restrictions]." This led to Operation Deny Flight. NATO later launched air strikes during Operation Deny Flight and during Operation Deliberate Force.
Lessons from Iraq and Bosnia
A 2004 Stanford University paper published in Journal of Strategic Studies, "Lessons from Iraq and Bosnia on the Theory and Practice of No-fly Zones," reviewed the effectiveness of the air-based campaigns in achieving military objectives. The paper's findings were: 1) A clear, unified command structure is essential. In Bosnia and Herzegovina, during "Operation Deny Flight," a confusing dual-key coordination structure provided inadequate authority and resulted in air forces not being given authority to assist in key situations; 2) To avoid a "perpetual patrol problem," states must know in advance their policy objectives and the exit strategy for no-fly zones; 3) The effectiveness of no-fly zones is highly dependent on regional support. A lack of support from Turkey for the 1996 Iraq no-fly zone ultimately constrained the coalition's ability to effectively enforce it.
As part of the 2011 military intervention in Libya, the United Nations Security Council approved a no-fly zone on 17 March 2011. The resolution includes provisions for further actions to prevent attacks on civilian targets. NATO seized the opportunity to take the offensive, bombing Libyan government positions during the civil war. The NATO no fly zone was terminated on 27 October after a unanimous vote by the UNSC.
Concerns about possible air attacks on the 2012 Olympic Games in London led to many precautions and layers of protection, including airspace zones that could be entered only with permission. No-fly zones are often put in place for events such as the 2017 G20 Hamburg summit.