Japan and the United States launched a joint naval drill today in a show of force aimed at North Korea, whose nuclear ambitions dominated US President Donald Trump's recent Asia trip. <br/><br/>The US navy said in a statement in Tokyo that the 10-day exercise will take place in waters surrounding Okinawa in southern Japan. It said that the annual drill is designed to increase the defensive readiness and interoperability of Japanese and American forces through training in air and sea operations. <br/><br/>The statement said 14,000 US servicemen, aircraft carrier USS Ronald Reagan and the guided-missile destroyers USS Stethem, USS Chafee and USS Mustin, among others are participating in the drill. It comes after three US aircraft carriers held rare joint drills in the western Pacific, joined separately by Japanese navy and South Korean warships over the weekend.<br/><br/>North Korea, which has stoked regional tensions with nuclear and missile tests in recent months, has repeatedly denounced such military drills as rehearsals for invasion and sometimes conducts its own military manoeuvres in response.