How No-fly Zones Work

In spring 1991, the United States and allies expelled Iraqi dictator Saddam Hussein's forces from neighboring Kuwait. Iraq's long-oppressed Kurdish minority, encouraged by American radio broadcasts, staged a revolt in northern Iraq.

In response, Saddam sent helicopter gunships armed with napalm and chemical weapons to rout the rebels. Hundreds of thousands of Kurdish civilians fled the brutal onslaught, and became trapped on barren hillsides near the Turkish border without food or water. U.S. President George H.W. Bush and his European allies found themselves in an agonizing situation. They were reluctant to remove Saddam from power, but didn't want to see a humanitarian disaster they'd inadvertently instigated [source: Globalsecurity.org].

Instead, they hit upon a solution. In April 1991, the U.N. passed another resolution condemning Hussein's repression of the Kurds and called upon member nations to assist in relief efforts. U.S., British and French air forces moved in and launched a massive supply and rescue operation. The resolution warned Hussein not to interfere with relief efforts, and the allies used that authority to declare what may have been the first no-fly zone in history — a 19,000-square-mile (49,209-square-kilometer) area north of the 36th parallel.

In 1992, a second no-fly zone was imposed south of the 33rd parallel, to protect Shi'ite Muslims who had also rebelled. When Saddam violated the no-fly zones, the coalition forces punished those infractions with force — either by shooting down Iraqi regime aircraft, or by destroying Iraqi military targets with missiles. The ban continued until the United States invaded Iraq to overthrow Saddam in 2003 [source: BBC News].

The breakup of Yugoslavia in the early 1990s, and the bloodshed that resulted, led NATO forces to impose another U.N.-authorized no-fly zone in 1993 over the breakaway region of Bosnia and Herzegovina. Operation Deny Flight was intended to block Bosnian Serbs, who controlled virtually all the military aircraft in the region, from attacking their Muslim neighbors from the air. The mission later was expanded, and NATO attacked Bosnian Serb anti-aircraft missile installations, artillery and armor in an effort to compel them to stop their aggression [source: Keating, Globalsecurity.org].

After a popular rebellion erupted against Libyan dictator Muammar Gaddafi in the spring of 2011, the U.N. Security Council passed resolution 1973, which banned all flights in Libyan airspace and authorized U.N. members to act individually or as a group to take "all necessary measures" to protect Libyan civilians [source: UN.org].

Because the concept of no-fly zones has been around for only about 30 years, and has been utilized only three times, there isn't yet a standard playbook for how they are to be set up and enforced.

For one thing, there's the question of where the U.S. or NATO gets the legal authority to impose a no-fly zone. One source of justification could be Chapter 7, Article 42 of the U.N. Charter, which states that if diplomacy isn't able to resolve a threat to international peace, the U.N. may authorize "demonstrations, blockade, and other operations by air, sea or land forces" [source: UN.org].

Thus, the first step to establishing a no-fly zone is to obtain a mandate from the 15-member U.N. Security Council. That usually requires some deft diplomacy, since any of the five permanent members — the United States, China, Russia, the U.K. and France — can block the action with a veto.

In the case of the Libyan no-fly zone, China and Russia opposed the plan but were persuaded by advocates to abstain from the vote [source: UN.org]. In Ukraine, though, that source of authority isn't available, because Russia, which has a permanent seat on the U.N. Security Council, most likely would block any no-fly zone resolution.

However, according to a research briefing released by the U.K. Parliament March 7, 2022, a no-fly resolution also can be established with the consent of the state whose airspace it protects. That would enable the elected government of Ukraine to authorize NATO to close off access to its airspace [source: Brooke-Holland and Butchard].

Once authority is established, there's also the question of what specific conditions should be imposed. In Libya in 2011, for example, the U.N. resolution laid out only the most basic parameters. It banned any flights in Libyan airspace, except for humanitarian missions to deliver medical supplies and food, or to evacuate foreign nationals from the conflict area. It also authorized member states to enforce the ban, provided that they notify the U.N. and report back on a monthly basis to detail their actions and provide information on any violations of the ban.

United Nations member were also authorized to deny permission to any aircraft to take off from, land in or overfly their own airspace, if they had reason to suspect that a plane is transporting weapons or mercenaries to Libya [source: UN.org].

One reason that imposing no-fly zones is so complicated is that the U.N. and the countries who'll provide aircraft, missiles and personnel have to agree on rules of engagement (RoEs), which spell out, among other things, when and how to confront possible violators, how much force can be used against them, and who authorizes taking action in such situations. We'll discuss the RoEs for no-fly zones and how they're carried out next.

Exactly which measures an international coalition takes to enforce a no-fly zone seems to vary quite a bit.

In Iraq, for example, coalition air forces operated under fairly restrictive rules of engagement so that they were forced to play cat-and-mouse with violators and only whittle away gradually at Iraqi anti-aircraft defenses. In Libya, in contrast, the U.N.'s broad authorization of "all necessary measures" gave NATO a lot of leeway [source: Robinson].

As a result, the first step in Operation Odyssey Dawn, as the 2011 Libyan mission was dubbed, was not a patrol, but an attack. On day one, U.S. Navy ships and a British unleashed a barrage of 112 Tomahawk cruise missiles on 20 Libyan military targets, crippling Gaddafi's radar, command-and-control infrastructure and anti-aircraft missile installations. The goal was to "shape" the battle space to reduce the risk to NATO pilots who eventually would patrol it [source: Robinson, Knickerbocker].

After high-altitude U.S. pilotless, drone surveillance aircraft were sent in to assess the first day's damage, U.S. Navy radar-jamming aircraft began flying over Libya as an added measure to neutralize what remained of Gaddafi's air defenses and to prevent his small air force of aging 1960s-vintage fighter jets from getting into the air. At the same time, aircraft from the United States and other NATO forces began to pound Libyan military targets, with the aim of further reducing his ability to attack rebels and civilians [source: Robinson, Knickerbocker].

The air crews who patrolled Libyan airspace had a complicated job. According to a 2011 NATO article, the crews spent about four hours being briefed about the latest intelligence, studying weather data and the positions of other coalition aircraft, and preparing and checking their equipment and plane before taking to the sky. Once in the air, they received a second intelligence update from surveillance aircraft, and then cruised around the area, watching for any planes to enter the no-fly zone. If one was spotted, they had to determine whether it was a "hostile" aircraft, or one that had simply entered the airspace by mistake. Before taking any action against the intruder, they generally had to obtain clearance from a commander on the ground [source: Booth].

In Ukraine, establishing a no-fly zone would be vastly more complicated, because of the risk of a confrontation with Russia. A March 4, 2022, article by the German Marshall Fund advocated a less-stringent alternative version, in which three countries bordering Ukraine — Poland, Slovakia and Romania — might declare 62-mile (100-kilometer) wide zone from their borders to be a humanitarian zone, which would allow Ukrainian refugees to flee without threat of being attacked by the Russians.

NATO, which would enforce the limited no-fly zone, would establish rules of engagement in which its warplanes wouldn't automatically shoot at Russian aircraft, but would instead intercept them or disrupt their movements with approaches and close passes [source: Hegedus]. An open letter led by Robert McConnell, co-founder of the U.S.-Ukraine Foundation and signed by 27 former national security officials and scholars, advocated such an approach.

That alternative, however, wouldn't protect Ukraine's cities from attack by the Russians, and Ukrainians who didn't want to become refugees would still remain vulnerable.

Enforcing the Libyan flight ban over an extended period was a major challenge for NATO, since Libya covers 680,000 square miles (1,761,191 square kilometers). On the plus side, most of the population lived on 10 percent of the land, in a narrow region along the coast [source: France24]. A March 2011 analysis by the Center for Strategic and Budgetary Assessments estimated the cost of imposing a no-fly zone over the entire country for a six-month period at $3.1 billion to $8.8 billion [source: Harrison and Cooper].

Additionally, no-fly zones necessitate risks to NATO pilots. In Bosnia in 1995, U.S. Air Force Capt. Scott O'Grady's F-16 was hit by a surface-to-air missile. Grady was forced to eject and parachute into Serbian-held territory. Relying upon his survival training, he spent six harrowing days evading Bosnian Serb pursuers, eating ants and catching rain in a plastic bag for drinking water. Fortunately, he was able to establish radio contact with a U.S. search plane, and eventually was rescued by a team of Marines [source: Fedarko].

In Iraq, Saddam Hussein reportedly offered a $14,000 reward in the late 1990s to anyone who could shoot down a coalition aircraft, but fortunately no one ever was able to collect [source: Correll]. Even in Libya, where anti-aircraft defenses had been been destroyed, NATO airplanes still faced the threat of shoulder-fired missiles.

Imposing a no-fly zone in Ukraine also would entail even greater risks than in the past. NATO pilots would be vulnerable to attack not just from Russian ground forces and aircraft within Ukraine, but by S-400 surface-to-air missiles launched from inside Russia itself, unless those systems were destroyed [source: Nevitt]. That would require escalating the conflict to a very dangerous level.

Critics of no-fly zones also question whether they actually achieve their intended purpose of preventing despotic regimes from killing their own people. In Bosnia, for example, the no-fly zone failed to prevent Bosnian Serb forces from laying siege to Srebrenica and massacring 7,000 Bosnian Muslim men and boys there in 1995 [source: BBC News].

It's hard to find research data showing the effectiveness of no-fly zones in reducing civilian casualties. Critics have argued that their impact is limited, because no-fly zones focus upon eliminating threats from the air, but don't stop ground-based attacks. In Iraq and Bosnia, for example, Saddam Hussein and the Serbs both shifted to tanks, artillery and infantry to continue the killing [source: Renner, Benitez and Pietrucha]. To completely stop such violence, it might be necessary to augment a no-fly zone with ground troops.

Even so, agonizing images from Ukraine of apartment buildings and hospitals demolished by airstrikes, and bloodied civilian survivors crying out in anguish over the loss of life, form a powerful argument in favor of a no-fly zone that dispassionate analysis can't totally refute.

As Ukrainian President Zelensky recently chided NATO countries, saying that if they didn't impose a no-fly zone or give the Ukrainians aircraft to protect themselves, there can be only one conclusion: You want us to be slowly killed" [source: Saric].