Why did Libyan troops enter Chad in 1980?

Libyan troops entered Chad in December 1980 at the specific request of President Goukouni Oueddei.12

At the time, the country was embroiled in a civil war that had evolved into a power struggle between competing northern political factions. The intervention occurred during this period of internal instability, as Goukouni sought military support to bolster his position against rival forces, such as the Armed Forces of the North (FAN) led by Hissène Habré.12

While this specific deployment was made at the president's invitation, it is important to note that Libya had previously occupied the Aozou Strip in 1973 and unilaterally annexed it in 1975, fueling a long-standing sovereignty dispute between the two nations.3