Zeman called for unified armed operation against Islamic State (ISIL) led by the U.N. Security Council. In June 2015, Zeman commented that: "If European countries accept a wave of migrants, there will be terrorist groups among them, of which also a Libyan minister has warned. By accepting the migrants, we strongly facilitate Islamic State’s expansion to Europe." Zeman described the Middle Eastern refugees arriving in Europe as an "organized invasion". In September 2015, Zeman rejected the European Union's proposal of compulsory migrant quotas, saying, "Only the future will show that this was a big mistake".