Task: Question Generation
Input (English): Passage: Fighting continued throughout the winter between the KDP and PUK. Complicating matters, PKK was present in Iraq. PKK was allied with the PUK which later led KDP attack the PKK. According to some sources, the PKK began to fight against all who supported KDP, including some Assyrian and Arab groups. Turkey which saw the Kurdish Civil war as an opportunity, allied with KDP and launched Operation Hammer in May, in a violent attempt to force the PKK to leave Iraqi Kurdistan. This operation caused heavy PKK casualties but was unsuccessful. PKK succeeded to keep their camps in Northern Iraq. On 25 September 1997, Turkish forces re-entered Iraqi Kurdistan and attacked PUK and PKK positions in an attempt to force the PKK to leave Iraqi Kurdistan. However, according to Turkish sources, it was an attempt to bring a cease-fire between the factions. The operation resulted in heavy PKK and PUK casualties. Later a cease-fire was negotiated between the PUK and KDP after the US decision to support a cease-fire. Despite the cease-fire, renewed fighting broke out along the armistice line between the KDP and PUK in October and November. In this round of fighting, 1,200 combatants were killed on both sides and 10,000 civilians fled their homes. On 24 November 1997, the KDP declared a unilateral cease-fire. The PUK, although not declaring a cease-fire officially, said their group would respect the truce, despite alleging that the KDP had violated the truce by attacking PUK positions on 25 November.
Output (English): How many months after launching Operation Hammer did Turkey re-enter Iraqi Kurdistan?