Dr. M. Khan the translator of Sahih Bukhari and the Quran into English writes:
"Allah revealed in Sura Bara'at the order to discard (all) obligations (covenants, etc), and commanded the Muslims to fight against all the Pagans as well as against the people of the Scriptures (Jews and Christians) if they do not embrace Islam, till they pay the Jizia (a tax levied on the Jews and Christians) with willing submission and feel themselves subdued (as it is revealed in 9:29). So the Muslims were not permitted to abandon "the fighting" against them (Pagans, Jews and Christians) and to reconcile with them and to suspend hostilities against them for an unlimited period while they are strong and have the ability to fight against them. So at first "the fighting" was forbidden, then it was permitted, and after that it was made obligatory " [Introduction to English translation of Sahih Bukhari, p.xxiv.]
http://www.faithfreedom.org/Articles/sina41019.htm