Complex sentence: On 21 December 1965 the National Command dissolved the Syrian Regional Command, and on 18 February 1966 Aflaq denounced the Jadid group as a "regional separatist" deviation.
Split into simpler sentences: On 21 December 1965 the National Command dissolved the Syrian Regional Command. On 18 February 1966 Aflaq denounced the Jadid group as a "regional separatist" deviation.