By now Thomas suspected that Mehmed also intended to conquer his kingdom. Therefore, he started taking more interest in a Christian coalition against the Turks, and cooperating more closely with his father-in-law. The lack of a firmer action against the Ottomans was blamed on Bosnian Christians, whom he described as being more inclined towards the Muslims than towards other Christians. The heavy Ottoman defeat by Hungarians at the Battle of Belgrade in July 1456 did nothing to alleviate Thomas' situation, as Mehmed started exerting an even greater pressure on Bosnia. In addition to financial extortion, Thomas was now forbidden to export silver, which Mehmed claimed for himself. This severe crippling of the Bosnian economy suffocated the kingdom.