After he was appointed Commander of NATO's Allied Rapid Reaction Corps (ARRC), Jackson was promoted to acting lieutenant general in January 1997, a rank he was granted substantively in April 1997. Jackson served in the NATO chain of command, reporting to the Supreme Allied Commander Europe, American four-star General Wesley Clark. Under Jackson's command, the ARRC deployed to Bosnia and Herzegovina in March 1999, where Jackson served his second tour of duty in the Balkans, commanding KFOR, NATO's multi-national peacekeeping force established at the end of the Kosovo War. He gained significant media attention in June 1999 after a confrontation with Clark in which he refused to block the runways of the Russian-occupied Pristina Airport and isolate the Russian troops there, thus preventing them from flying in reinforcements. In one heated discussion with Clark, Jackson reputedly told him "I'm not going to start the Third World War for you". He later told the BBC he believed that obeying the order would have led to the possibility of an armed confrontation with Russian troops, which he felt was not "the right way to start off a relationship with Russians". The point became moot when the US government prevailed upon neighbouring countries, including Hungary and Romania, to prevent Russian use of their airspace to fly in reinforcements. Jackson was criticised for his actions by American military officers and politicians, including General Hugh Shelton, Chairman of the Joint Chiefs of Staff, who called the incident "troubling", and Senator John Warner, who accused Jackson of insubordination.