Japan and the United States launched a joint naval drill Thursday in a show of force aimed at the Democratic People's Republic of Korea (DPRK), whose nuclear ambitions dominated US President Donald Trump's agenda during his recent Asia trip. 

The 10-day exercise "will take place in waters surrounding Okinawa" in southern Japan, the US Navy said in a statement. The naval drill is joined by some 14,000 US servicemen, the aircraft carrier USS Ronald Reagan and the guided-missile destroyers USS Stethem, USS Chafee and USS Mustin, among others.

The DPRK, 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. 

The annual drill "is designed to increase the defensive readiness and interoperability of Japanese and American forces through training in air and sea operations," the US Navy said, according to AFP.

It comes after three US aircraft carriers, including the USS Ronald Reagan, held rare joint drills in the western Pacific, joined separately by the Japanese navy and South Korean warships over the weekend. Those drills were slammed by DPRK's Ambassador Ja Song Nam, who said in a letter to UN Secretary-General Antonio Guterres this week that the current situation was "the worst ever" around the Korean Peninsula. 

As the drill kicked off, Japanese Prime Minister Shinzo Abe met the commander of the US Pacific fleet, Harry Harris, and urged "close coordination" between Tokyo and Washington to "enhance deterrence" amid the DPRK threat.

The DPRK conducted its sixth nuclear test this year and test-fired a series of advanced missiles, including intercontinental ballistic missiles. 

 On Wednesday, Trump vowed a global campaign of "maximum pressure" on the DPRK, warning Pyongyang will not subject the world to "nuclear blackmail."