In the meantime, however, the Order had been looking for other allies. In 1512, Muscovy invaded the Grand Duchy of Lithuania, which was in personal union with Poland. The Order was supposed to help the Duchy, but it refused, angering Sigismund I. In 1517, the Teutonic Order signed an alliance with Vasili III of Muscovy. Albert now felt he held the upper hand and demanded from the Polish king the return of Royal Prussia and Warmia territories, as well as a large remuneration for "Polish occupation" of those territories. In response, first the diet of Prussia (Landtag or sejmik), and then, in December 1519, the main Polish sejm, declared that a state of war existed between the Polish Kingdom and the Order. Lithuania refused to aid Poland, however, as it was occupied with the Muscovy threat.