In yet another attempt to show strength amid rising regional tensions, North Korea launched two ballistic missiles off the east coast Monday, according to the South Korean military, as US nuclear-capable submarine enters Seoul’s naval base.

The Japanese defence ministry also reported the launch of ballistic missiles by North Korea, both of which fell outside its exclusive economic zone (EEZ).

The ballistic missile firing comes as the region is witnessing heightened tensions with Korea exchanging nuclear threats and the US expressing its resolve against Pyongyang if its allies were attacked.

Both the US and its allies are increasing their military cooperation to meet any aggression from North Korea, with military drills and combat readiness. Last week, US nuclear-capable submarine arrived South Korean coast citing tensions with North Korea.

North Korea responded aggressively with a nuclear threat saying such a deployment could meet the criteria for its use of nuclear weapons on Seoul.

The United States said it was consulting closely with its allies about the North Korean missile launches, which it described as being destabilising.

In a statement Monday, the US military added the launches posed no immediate threat to US personnel and territory or to US allies.

“Earlier Monday, a nuclear-powered US submarine entered a naval base in South Korea’s southern island of Jeju to load military supplies while on an unspecified operational mission,” the South Korean Navy said.

Last week, North Korea had launched two intercontinental ballistic missiles (ICBMs) just after the submarine’s arrival after four decades to protect South Korea and US allies from Kim Jonh Un’s aggression.

The Japanese Defence Ministry said at that time that both the missiles appeared to have fallen outside Japan’s EEZ.

The firing came a week after North Korea tested its latest Hwasong-18 ICBM, a launch Pyongyang said was a warning to the US and adversaries.

Also, last week, Tuesday, a US soldier Private 2nd Class Travis King, who was being escorted back to the US for disciplinary reasons entered North Korea, sparking a fresh crisis between Washington and Pyongyang.

“North Korea’s latest firing of ballistic missiles is probably unrelated to an American soldier crossing the inter-Korean border, but such an incident doesn’t help matters either,” said Leif-Eric Easley, a professor at Ewha University in Seoul.