Complex sentence: On 6 June, the FAN assumed control of the city of Faya; this alarmed Goukouni, and he signed, on 15 June, a Treaty of Friendship with Libya.
Split into simpler sentences: On 6 June, the FAN assumed control of the city of Faya. This alarmed Goukouni, and he signed, on 15 June, a Treaty of Friendship with Libya.