The United States Department of Defense believes the YJ-18 is similar to the Russian 3M-54 Klub, with a subsonic cruise mode and a supersonic terminal attack;[6] the missile is credited with a range of 290 nautical miles (330 mi; 540 km),[7] which would give it a threat ring of 264,200 sq nmi (349,900 sq mi; 906,000 km2).[3] Some Western analysts believe the YJ-18 is a copy of the 3M-54E, with a cruising range of 180 km (110 mi; 97 nmi) at Mach 0.8 and a sprint range of 40 km (25 mi; 22 nmi) at Mach 2.5 to 3.0;[4][1] other sources claim the submarine-launched variant has a range of 500 km (310 mi; 270 nmi) with a terminal speed of Mach 2 while flying at a lower terminal altitude than the Russian Kalibr/Klub.[8]