Two Japanese destroyers began a joint drill with a group of US warships in the Western Pacific Ocean on Sunday in the face of a growing nuclear threat from North Korea, the US Navy said, according to dpa. The destroyers Samidare and Ashigara and US warships, including aircraft carrier USS Carl Vinson, will carry out strategic manoeuvres and communication drills for several days. "The routine exercise is designed to improve combined maritime response and defence capabilities, increase combined manoeuvring proficiency, and ensure maritime forces remain ready to defend the region when called upon," according to the Carl Vinson's Facebook page. The relationship between the Japanese and US navies "is better than ever and it's in part thanks to these bilateral exercises," Rear Admiral Jim Kilby, commander of the carrier strike group, said on the Facebook posting.