US President Donald Trump has fired a shot across the bows of North Korea by announcing the installation of a US missile defence system in South Korea and despatching a US guided-missile submarine to the region.

Mr Trump’s decision to set up the Terminal High-Altitude Area Defence system, or THAAD, comes as high-powered US military hardware converges on the Korean Peninsula and as a combative North Korea flags possible nuclear and missile testing.

It also comes a day after rival North Korea showed off its military power and conducted live-fire artillery drills to mark the 85th anniversary of the founding of its million-person strong Korean People’s Army.

A US guided-missile submarine has docked in South Korea, and the USS Carl Vinson aircraft carrier is headed toward the peninsula for a joint exercise with South Korea.

The moves to set up THAAD within this year have angered not only North Korea, but also China, the country that the Trump administration hopes to work with to rid the North of nuclear weapons.

China, which has grown increasingly frustrated with its ally Pyongyang, and Russia see the system’s powerful radars as a security threat.

South Korea said in a statement on Wednesday that unspecified parts of THAAD were installed, and Yonhap news agency reported the parts include two or three launchers, intercept missiles and at least one radar.

The statement said that Seoul and Washington have been pushing to get THAAD quickly working to cope with North Korea’s advancing nuclear and missile threats.

On Tuesday, North Korea conducted live-fire drills near the east coast city of Wonsan that involved 300 to 400 artillery pieces, Yonhap reported. An official from Seoul’s Defence Ministry couldn’t confirm those specific details.

North Korea’s official media said early Wednesday that leader Kim Jong Un personally observed the exercises.

The drills reportedly included submarine torpedo attacks on mock enemy warships “while fighters and bombers made zero feet flight above the sea to drop bombs on the targets,” the Korean Central News Agency said.

Chinese President Xi Jinping, who spoke to Trump on Monday, is urging restraint from both Pyongyang and Washington where top administration officials are due to brief the entire US Senate on Wednesday.

TIMELINE OF TENSIONS

FEBRUARY

13 – North Korea is blamed after Kim Jong-nam, the estranged half-brother of leader Kim Jong-un, is murdered in a Cold War-style assassination at a Malaysian airport.

MARCH

6 – North Korea test fires four ballistic missiles, three of which fall into Japan’s exclusive economic zone.
28 – A US think tanks says satellite imagery indicates Pyongyang could be in the final stages of preparations for a sixth nuclear test.

APRIL

9 – President Donald Trump orders the USS Carl Vinson carrier strike group to sail to waters off the Korean peninsula.
11 – North Korean state media warns it is prepared to launch a nuclear attack on the US at any sign of aggression.
15 – A mock-up video is shown in North Korea depicting the US being hit by a nuclear bomb as North Korea celebrates 105 years since the birth of its founding president Kim Il-sung.
16 – An attempt to conduct another missile test fails when it blows up up almost immediately after being launched from a submarine base on North Korea’s eastern coast.
18 – A senior North Korean official tells the BBC the country will continue to test missiles regularly and military action by the US will prompt “all out war”.
24 – North Korea threatens a nuclear strike against Australia if Canberra continues to “blindly and zealously” toe the US line. North Korea state media also say they’re ready to strike the US air carrier.
25 – Live-fire drills are conducted near the east coast city of Wonsan, involving 300 to 400 artillery pieces as part of the 85th anniversary of the Korean People’s Army; a US guided-missile submarine docks in South Korea.
26 – The US begins installing parts of the THAAD missile defence system in South Korea.