The Reagan administration, still smarting from attacks on its Central American actions, may be looking to score quick foreign policy points by taking a tough stance against Libyan leader Muammar Qaddafi.
The White House stance is aimed at curtailing Colonel Qaddafi's backing of rebels fighting in Chad and reported bombing raids this week by Libyan jets in northern Chad.
The United States response has included stationing the US carrier Eisenhower off the Libyan coast. In addition, the US is sending $10 million in military aid , including 30 anti-aircraft missiles and three military advisers to Chad.
According to observers the arrival of three American military advisers here is the best indication of increased US concern about reported Libyan intervention in the civil war, including Libyan air attacks on President Hissein Habre's troops in Faya-Largeau.
The State Department and the Quai d'Orsay, France's Ministry of External Relations, say that the French and the US are cooperating to fashion an ''appropriate response'' to the direct Libyan intervention in the fighting in Chad. But the feeling among Western diplomats and observers in N'Djamena is that it is now the Reagan administration and not the French that is taking the lead in confronting Qaddafi.
As one Western official commented, ''The French have an ambiguous, a kind of love-hate relationship with Qaddafi which prevents them from confronting him directly. The Americans do not have such a problem. When they see Qaddafi making a move, they act quickly.''
Although the French continue to supply a substantial amount of military hardware to Habre's forces and French ''civilian'' pilots continue to fly that equipment from N'Djamena to Faya-Largeau, the events of the last few days lend substance to the conclusion that it is now the US that is taking the lead in supporting the Chadian government.
This is reflected in the sending of the carrier Eisenhower into the Gulf of Sidra, as well asthe sending of two AWACS to Egypt before scheduled air exercises with Egyptian forces next week. The airborne warning and control system (AWACS) planes could be used to monitor any Libyan air activity over Chad.
(For its part, Libya has not backed down before the US show of force. The Libyan news Agency Jana - still denying Libyan involvement in the bombings of Faya-Largeau and other northern Chad cities - warned any foray by foreign vessels into the Gulf of Sidra would be met with air attacks.
(In Washington, State Department spokesman John Hughes said the US had ''no response except to say that we recognize a 12-mile territorial limit and we retain our right to operate in international waters.''
(Libya's claim to the 300-mile-wide gulf is rejected by Washington and most other governments.)
According to reliable Western sources in N'Djamena, it was the US that reacted first to the Libyan air attacks and to the Chadian government's request for increased assistance by flying in 30 Redeye hand-held antiaircraft missiles before similar French weapons arrived.
In addition, it is US advisers who are now training Chadian troops in the use of those missiles. The missiles should become operational by the weekend.
This apparent switch in the roles of the US and French governments has not been lost on Chadian officials. In recent days these officials have attempted to strike an increasingly responsive chord with the Reagan administration by stressing the East-West ramifications of the conflict.
''The Soviet Union is using Libya for its own purposes,'' Chadian Foreign Minister Idriss Miskine stated in a recent interview with Agence France-Presse. ''It is the Russians who are arming the Libyans and pushing Qaddafi to destabilize Africa to extend their hegemony.''
The Libyans are reportedly using Soviet-built Sukhoi bombers in their raids on Chad.
In an attempt to solicit increased US military assistance, the Chadian minister of information, Soumaila Mahamat, in his daily press conferences echoed the fears of the Reagan administration that a Libyan-influenced Chad could destabilize the entire central and east African region. Such a development would threaten such US friends as Egypt, the Sudan, and Nigeria.
As the minister said recently, ''Chad is simply at the forefront, and a victory for Libyan and Soviet expansionism here would be a blow to all neighboring African countries.''
According to the State Department, the recent increase in US military assistance to Chad remains within the original $10 million allotted to Chad by the Reagan administration last week.
Whether that will remain the case after the recent increase in Libyan air attacks at Faya-Largeau, and farther south at the strategic towns of Oum Chalouba and Kalait, remains to be seen.