Qaddafi has a track record of misadventures extending back to the Libyan revolution, which brought him to power at the head of a military junta in 1969. He supported terrorism all over the world and had a penchant for stirring up trouble in Africa. In the late 1970s he sent troops to support Ugandan President Idi Amin, who was under assault from opponents coming from Tanzania. And in 1983, he launched a massive invasion (by African standards) of his neighbor to the south, Chad.
Chad was of no particular importance to the United States. It was part of Francophone Africa, and the French had the primary interest there among Western countries. Moreover, any resources the country had were in the south (deemed "Tchad Utile" -- useful Chad -- by the French), not in the desert north occupied by Libya. Indeed, it would be hard to think of a more useless part of the planet.
Nevertheless, Washington did not want to be seen as acquiescing to Colonel Qaddafi's invasion of another country -- even if it was only Chad. Bear in mind that 1983 was an extraordinary year of regional turmoil: The Iran-Iraq war was endangering oil flows in the Persian Gulf, the U.S. Embassy in Beirut was attacked in April and the Marine barracks in October, the Soviets shot down Korean Air Lines Flight 007 in September when it strayed over their territory, U.S. troops invaded Grenada in October, the Iraqi Islamic Dawa Party (with ties to the current leadership in Baghdad) conducted attacks in Kuwait including bombing the U.S. Embassy, and Donald Rumsfeld visited Saddam Hussein in December in Baghdad as the United States began to tilt toward Iraq to contain Iran. On the global strategic level, U.S. President Ronald Reagan's "Star Wars" initiative, announced in March 1983, threatened to upset the balance of power between the United States and the USSR.
I happened to be in the State Department's Political-Military Bureau at the time. Among my other duties, I was given responsibility for security assistance to Chad in response to the Libyan invasion.
With so much on the agenda of senior officials, there was -- by today's standards -- a lot of flexibility given to lower-level experts and operations officers. From our perspective, the Libyan problem was one that the United States could address, within certain political limits. The key point was that we did not want to get out ahead of the French in Chad. Nor did Washington want to inadvertently inherit Chad as "its" problem. We had enough other crises on our plates. Nevertheless, we did not want Qaddafi -- or anyone else, for that matter -- to think that the United States would acquiesce to such aggression without paying a price.
The policy goal was therefore pretty clear -- and limited. At the working level, we considered what we could do to assist the limited Chadian "army" in repulsing the Libyan invasion. Then as now, Libyan forces had better equipment than personnel and leadership. They were kitted out with all sorts of Soviet helicopters, aircraft, surface-to-air missiles, tanks, and armored personnel carriers. And given the vast expanses of territory involved, they had very, very long logistics lines with not much in the way of logistical support.
The Chadians were very poorly equipped. But they had a distinct advantage because most were tribesmen from northern Chad and were accustomed to the bleak desert that the Libyans were now occupying in a handful of military bases at remote places like Faya-Largeau, Fada, and Ouadi Doum (pronounced "doom," and so it was for many of the Libyans sent there). The Chadians were also motivated to defend their land, while the Libyans only wanted to survive and go home as soon as possible.