 In spring 1943, the OUN-B's UPA launched a campaign of murder and expulsion against the Polish population of Volhynia, and in early 1944 against the Poles in Eastern Galicia.This was done as a preemptive strike, in expectation of another Polish-Ukrainian conflict over the disputed territories, which were internationally recognized as part of Poland in 1923.The Polish government in exile wanted to restore eastern Polish borders beyond the Curzon Line, an aim that was also supported by promises from the Western Allies.