North Korea announces it has ordered artillery and rocket units into “combat posture” to prepare to target US bases in Hawaii, Guam and the US mainland.

The announcement, carried by KCNA news agency, follows days of strong rhetoric from Pyongyang.

The north Korean move came as South Korea marked the third anniversary of the sinking of the Cheonan warship, which left 46 sailors dead.

South Korea said it had detected no signs of unusual activity in the North.

Tensions remain high on the Korean peninsula in the wake of North Korea’s third nuclear test on February 12. The test led to new UN sanctions which Pyongyang strongly opposes.

Joint US-South Korea annual military drills have further angered the communist nation. In recent weeks its habitually fiery rhetoric has escalated – it has threatened the US with “pre-emptive nuclear attacks”, as well as strikes on US military bases in Japan.

“From this moment, the Supreme Command of the Korean People’s Army will be putting in combat duty posture No 1 all field artillery units including long-range artillery units and strategic rocket units that will target all enemy objects in US invasionary bases on its mainland, Hawaii and Guam,” the KCNA statement said.

North Korea announces it has ordered artillery and rocket units into “combat posture” to prepare to target US bases in Hawaii, Guam and the US mainland

North Korea is not thought to have the technology to strike the US mainland with either a nuclear weapon or a ballistic missile, but it is capable of targeting US military bases in the region with its mid-range missiles.

North Korea’s announcement comes as the country carries out large-scale military exercises, and it is not clear whether the order applies to the army as a whole or just to specific units.

In a press briefing, Chinese Foreign Ministry spokesman Hong Lei said that he hoped that “relevant parties [would] exercise restraint so as to ease the tension”.

The statement came hours after South Korean President Park Geun-hye called on North Korea to “change course” by abandoning nuclear weapons.

Speaking at the national cemetery in Daejeon where the sailors who died when the warship sank are buried, Park geun-hye said North Korea continued to threaten the South’s national security.

“For the North, the only path to survival lies in stopping provocations and threats, abandoning its nuclear weaponry and missiles, and becoming a responsible member of the international community,” she said.

The Cheonan sank in 2010 near the disputed inter-Korean western maritime border. South Korea says a North Korean torpedo sank the ship but Pyongyang denies any involvement.

Months later, North Korea shelled a border island, Yeonpyeong, in the same area, killing four South Koreans, including two civilians. It said it was responding to military exercises in the South.

Last week, South Korea and the US signed a new military plan – conceived after the shelling – pledging joint action to counter limited attacks from North Korea.

Meanwhile, websites of associations for North Korean defectors said that their networks crashed earlier on Tuesday. They said that they were victims of a cyber-attack.

Officials said that South Korean broadcaster YTN’s network and a computer network used by seven local governments were also briefly paralyzed, Yonhap news agency reported.

Daily NK, a news site focused on North Korea, said in a post on its Facebook page that it had “experienced a cyber-attack at 13:40” local time on Tuesday.

Free North Korea Radio, a radio broadcaster, also said that its website “was completely destroyed” after an attack around noon, Yonhap reported.

The presidential office, Cheong Wa Dae, said in a statement that the government was “closely working to confirm if the paralysis cases were caused by technical problems or hacking attacks”.

A cyber-attack on six South Korean banks and broadcasters last week disrupted 32,000 computers and some banking services.

The origin of the attack is not yet known, although there has been speculation that North Korea could have been to blame.

North Korea has been blamed for previous cyber-attacks on the South in 2009 and 2011.

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