South Korea says it wants to re-establish lines of communication with North Korea, as new President Moon Jae-in seeks a two-track policy involving sanctions and dialogue with its reclusive neighbour to rein in its nuclear and missile programmes.

The two countries are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty. The North has ignored calls to curb its weapons programmes, defending them as necessary to counter US hostility.

Its latest ballistic missile launch, in defiance of UN Security Council resolutions, was on Sunday which it said was a test of its capability to carry a "large-size heavy nuclear warhead".

"Our most basic stance is that communication lines between South and North Korea should open," Lee Duk-haeng, a spokesman for the South's unification ministry, told reporters on Wednesday.

"The unification ministry has considered options on this internally but nothing has been decided yet."

Communications were severed by the North last year, Lee said, in the wake of new sanctions following North Korea's last nuclear test and Pyongyang's decision to shut down a joint industrial zone operated inside the North.

There was no immediate response from Pyongyang.

'Softer position'

Al Jazeera's Andrew Thomas, reporting from the South's capital, Seoul, said Lee's statement "refers effectively to a hotline.

"There is a room on the South Korean side of the border, and a room on the North Korean side of the border, and a physical line between the two which has been there since the 1970s and is used to relay messages of emergencies," he said.

"But since February 2016, the North has not been picking up - that communication has been effectively obsolete."

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Thomas said Seoul's announcement appeared to indicate "a softer position" compared with the rhetoric at the United Nations headquarters in New York, where the Security Council weighed new sanctions on Pyongyang.

"This is very different from dialogue, or talks, or anything approaching what might come down the line - but at its most basic it is a sign that the South’s new government is trying to be more reconciliatory towards the North despite Sunday's successful test on Sunday and Washington's talks of sanctions at the UN," Thomas said.

The US said on Tuesday it believed it could persuade China to impose new sanctions on North Korea and warned that it would also target and "call out" countries supporting Pyongyang.

Speaking to reporters ahead of the Security Council meeting, Nikki Haley, Washington's envoy to the UN, said that the US would talk to North Korea only once it halted its nuclear programme.

Talks in the US

Moon won an election last week campaigning on a more moderate approach to the North and said after taking office that he wants to pursue dialogue as well as pressure to stop the North's weapons programmes.

Moon's envoy to the US, South Korean media mogul Hong Seok-hyun, left for Washington early on Wednesday. Hong said he would discuss North Korea with high-ranking US officials.

Hong said South Korea had not yet received official word from Washington on whether it should pay for an anti-missile US radar system that has been deployed outside Seoul.

US President Donald Trump has said he wants South Korea to pay for the Terminal High Altitude Area Defense (THAAD) anti-missile system which detected Sunday's launch.

China has strongly opposed THAAD, saying it can spy into its territory, and South Korean companies have been hit in China by a nationalist backlash over the deployment.