Cautious Air Campaign
When NATO military planners were ordered in November 1998 to prepare for an air campaign against Yugoslavia, NATO commander General Clark initially ordered a "no loss of aircraft" restriction, translating political wishes of NATO governments, in particular the US and some European allies.
The Pentagon's Air Force Operations center used computer models with various variables such as size and range of Yugoslav air defense batteries, size and range of anti-aircraft artillery, number of shoulder-fired rocket systems, power of command and control communications links, and the likelihood of MiG fighters. The NATO strategy was altered in such a way that the number of lost planes was reduced to zero.
According to specialists, the United States Air Force doctrine would have called for hitting Yugoslavia hard the first few nights with a series of strong attacks on command and control centers, electrical and radio facilities, government buildings, and key bridges. Instead, a set of mild strikes were ordered, mainly ship-launched cruise missiles and B-52s launching their weapons from a safe distance. After the campaign, in October 1999, Allied Force commander Lieutenant General Short criticized the political interference during the military campaign, preventing him from conducting a "classic" air campaign.
Due to NATO's cautious approach — aimed to limit danger to pilots — the bombing campaign failed for a long time to stop Milosevic's crackdown of the KLA and the ethnic cleansing of ethnic Albanians and to force Yugoslavia to accept NATO's conditions. Pilots were frustrated by the constraints limiting their effectiveness, suggesting NATO should loosen rules of engagement. After 53 days pilots were allowed to go well below a previously established 15,000-feet threshold, although pilots generally refrained from this.
Throughout the campaign, NATO always insisted that its strategy was working, although it may have taken longer than anticipated.
NATO relied solely on air power to fulfill its mission and to reach its objectives. Apart from the UK, none of the NATO countries seemed willing to consider a ground war to fulfill the mission, because of the risks involved for NATO troops in Yugoslavia. Well-equipped Yugoslav forces were expected to offer strong resistance and the terrain and the weather was thought to be in their advantage. Since the start of the operations in the Balkans no NATO soldier had died in combat.
The open way the British government considered an option including ground troops angered the Americans.
Right from the start of the operation, the US president ruled out the use of ground troops, possibly not to alarm voters or to prevent Russian suspicion against western allies. A possible allied ground war would have required full US backup. Another problem was that the infrastructure in the Balkans was not suited for setting up a very large scale force. The region lacked modern ports and airfields.
NATO started the campaign against Yugoslavia, but seemed to lack any exit strategy. On several occasions, NATO made it clear that air strikes would continue until all objectives were reached. On April 22, 1999, some US and British officials said it was prudent to consider whether NATO's military policy in Yugoslavia should be reversed to allow the deployment of ground troops. NATO SACEUR was asked to update the military assessment made in October 1998 that the Yugoslavia campaign should be limited to the air.
On day 18 of the campaign (April 10, 1999), the US announced plans to send 24 AH-64 Apache attack helicopters to the region. On day 29 (April 21, 1999) the first six arrived in Albania. Getting these assets ready for deployment was roughly estimated at a "few weeks", something that was described by CNN as a "disturbing lack of urgency." Nevertheless, the US had more high-value military assets deployed in the Balkan region than any other country. In the third week of the campaign, NATO commander Clark made a request for several hundreds of additional warplanes — amongst which A-10 attack planes — and expected other NATO members to contribute more planes as well. However, ground troops still seemed out of the question. Some US Congress members insisted that sending in ground troops was the only way to end the ethnical cleansing of Kosovo.
NATO countries seemed surprised by the swiftness with which the Serb military and special police forces continued their ethnic cleansing of the province of Kosovo, even after the start of the air campaign against Yugoslavia. A few days after the start of Operation Allied Force, NATO switched to "phase two", switching from phased bombing to a campaign of seamless bombing of Serbian military targets in Kosovo and Serbia. With the attack on April 21, 1999 on a Belgrade building housing the offices of Yugoslav President Milosevic's ruling party and one of Milosevic's mansions in Belgrade a day later, the third phase seemed to have started, although denied by NATO at first.
The air campaign originally consisted of three phases:
- Operation Allied Force started with attacks on Serb air defenses that were meant to "set conditions," or establish NATO's ability to conduct strikes when and where it desired.
- The next phase was designed to isolate Serb military forces. NATO targeted rail and road networks, fuel production and storage, and facilities that enable Milosevic to command and communicate with his armed forces.
- The last phase was intended to "decimate" Milosevic's forces in Kosovo and to break the back of his political support. NATO said the targets from the third category were classified, but it included political targets such as party offices and broadcasting facilities — similar to the targets of April 21, 1999.
NATO military targets included:
- Integrated air defense systems
- Command, control, communications (C3)
- Military supply routes
- Ground forces
- Petroleum, oil, lubricants
- Ammunition, military products
After two main oil refineries were destroyed, NATO claimed Serbian fuel production was halted. Officials claimed that Yugoslavia's ability to repair aircraft was reduced by 70 percent and its ammunition production by two-thirds. About 40 percent of the anti-aircraft batteries were destroyed. Before the campaign, the Serbs had some 240 aircraft, of which 100 were destroyed by the strikes. However, about 80 percent of the ground attack aircraft was still intact, and of the 300-400 Serbian tanks, only about four dozen were destroyed (15 May 1999).
On May 22, 1999, NATO claimed its 1,000 warplanes struck 556 individual pieces of heavy equipment in Kosovo, including 312 tanks, artillery pieces and armored vehicles. Seventy-five percent of surface-to-air missile sites were destroyed as well as 69 percent of MiG-29s, and 34 percent of other combat aircraft.
There were questions whether all targets were strictly military and whether that would be acceptable. Targets such as buildings for political parties, transmitters for TV and radio stations, and power plants are — strictly speaking — non-military. However, NATO always said Serbian television was a legitimate target because it was spreading propaganda about the allied air campaign. (See article Allied unity: US Condemned French Vetoes.)