Russia launched a volley of missiles toward the eastern Ukrainian city of Dnipro early Thursday morning, including a new type of ballistic missile that has North Atlantic Treaty Organization members on edge. The powerful next-level, multiple-warhead battlefield weapon, which has been analyzed by the Pentagon, has prompted NATO to hold an emergency summit on Tuesday. Among the cruise missiles intercepted in the assault was what the Defense Department has identified as a variant of the RS-26, an "experimental" intermediate-range ballistic missile (IRBM), a reconfigured Russian intercontinental ballistic missile, according to a U.S. official. While publicly, U.S. officials say Russia likely...