 Complete the following phrase:  Four years after the signing of the treaty, in 1721, the Safavid city of Shamakhi was sacked and looted by Lezgin rebels. Volynsky reported to Peter the Great on the considerable harm done to the Russian merchants and their livelihoods. The report stipulated that the 1721 event was a clear violation of the 1717 RussoIranian trade treaty, by which the latter had guaranteed to protect Russian nationals within the Safavid domains. With the Safavid realm in chaos, and the Safavid ruler unable to fulfill the provisions of the treaty, Volynsky urged Peter to take advantage of the situation and to invade Iran on the pretext of restoring order as an ally of the Safavid king. Shortly afterward, Russia used the attack on its merchants in Shamakhi as a pretext to launch the 