To be honest, it was still new for our land. But they'd been suffering for years in their homeland. We have taken it upon ourselves to help those who ask for it, who need for it, regardless of how it can affect us. Plus, if we'd left it alone, the wound would fester and infect others - even if we had never attacked him, he would have come after us in his mad quest for power. Best to cut that off before it grows.