NATO spokesman Col. Martin O'Donnell said the alliance is "ready to deter and defend as necessary," adding that NATO is "always thinking through and preparing for any number of scenarios." Officials pointed to a mounting pattern of incidents they believe may already be testing NATO's response. In May, Lithuania's prime minister was moved to an underground bunker after NATO jets were scrambled to intercept a drone flying toward Vilnius. The warning also follows the discovery of an explosive-laden drone near a Ukrainian cargo plane at Leipzig/Halle Airport in Germany, a major logistics hub for NATO and Ukrainian military supply flights. The device, found close to an Antonov Airlines aircraft, was carrying Semtex explosive, forcing the airport to close and prompting a counterterrorism investigation.