Commonwealth and strained its military might to the limit. In 1617, after yet another wave of Cossack raids, the Sultan sent a powerful force under Iskender Pasha to the Commonwealth borders. The army consisted of janissaries, Tatars and vassal troops form Transylvania, Moldavia and Wallachia (numbering up to 40,000). Żółkiewski met them near Busza (on the Jaruga River), but neither side could decide to attack, and letters between leaders had been exchanged since the start of Iskender's march. Żółkiewski had mostly magnate troops and no Cossack troops, as the Commonwealth waged war with Muscovy and with new Swedish aggression on Livonia at the same time, while the Ottomans were at war with Persia. Żółkiewski was forced to renounce all Polish claims to Moldavia through the Treaty of Busza (also known as the "Treaty of Jaruga") signed with Iskender Pasha. The treaty stated that Poland would not meddle in the internal affairs of Ottoman vassals in Transylvania, Moldavia and Wallachia, the Commonwealth was to prevent Cossacks from raiding lands in the Ottoman Empire, while ceding Khotyn. In return, the Turks promised to stop Tatar raids. Prelude to the next conflict (1618–1620) 1618 However, few of the treaty provisions were ever fulfilled. The Tatar raids resumed in 1618 (or perhaps even 1617), as commanders of the Dobruja and Budjak hordes left Iskender's camp during talks. At first, Żółkiewki could not divide forces and Tatars plundered unopposed, but he met the Iskender Pasha's force near Kamianets-Podilskyi (Kamieniec Podolski). On September 28, 1618, he drove it back while enduring heavy losses. In 1617 and 1619 Żółkiewski forced Cossacks to sign new agreements ("umowa olszaniecka" and "biało-cerkiewna"). Boats were to be burnt and raids were forbidden. In exchange, the Cossack register was expanded, and the annual subsidy to Cossacks from the Crown was increased. However, Cossack raids did not cease, especially as they were encouraged by Muscovy. In July 1618, after many warnings to the Commonwealth, the young and ambitious Sultan Osman II sent a letter to King Sigismund III with the threats of a new war and the burning of Kraków. Since the Ottomans were involved in large-scale war with Persia, this was no more than a warning at the time. However, Osman planned for a war against the Commonwealth, in order to compensate for the heavy losses sustained against Persia, where, in the Ottoman–Persian Wars of 1603–1611 and 1617–1618/19, the Ottoman Empire lost