The talks with Stephen Biegun, US President Donald Trump's special envoy, came after Pyongyang's defiant test of a sea-launched ballistic missile this week.

"The negotiations have not fulfilled our expectations and finally broke up... without any outcome. (It) is totally due to the fact that the US would not give up their old... attitude," envoy Kim Myong Gil told reporters in Stockholm.

The talks marked a resumption of dialogue after a Hanoi meeting in late February between Trump and North Korean leader Kim Jong Un failed to yield a breakthrough.

"The US raised expectations and offered suggestions like flexible approach, new methods and creative solutions but they have disappointed us greatly, and dampened our enthusiasm for negotiations by bringing nothing to the negotiation table," Kim Myong Gil said, adding that North Korea stood "at the crossroads of dialogue or confrontation".

- 'Greatly disappointed' -

The meeting place was a heavily guarded venue on an island off Stockholm, several hundred metres from the North Korean embassy, an AFP correspondent said.

As it got underway, Swedish Foreign Minister Ann Linde tweeted: "I am encouraged that US and (North Korean) working level delegations are currently in Sweden to hold talks".

Dialogue needed to reach denuclearization and peaceful solution," she said.

Similar-level talks on North Korea's nuclear disarmament were held in Stockholm in March 2018 and then in January this year.

- Diplomacy, military moves -

North Korea claimed to have entered a new phase in its defence capability with Wednesday's test of a submarine-launched ballistic missile -- the most provocative since Pyongyang began a dialogue with Washington in 2018.

North Korea frequently couples diplomatic overtures with military moves as a way of maintaining pressure on negotiating partners, analysts say, and may believe this weapons system gives it added leverage.

The Pentagon said Thursday the missile seems to have been launched from a "sea-based platform" and not a submarine.

Trump has said he sees no problem with a string of short-range rocket tests conducted previously by North Korea, while insisting his personal ties with the North's leader remain good.

- 'New phase' -

Photos carried by Pyongyang's official Rodong Sinmun newspaper showed a black and white missile emerging from the water and appearing to shoot into the sky.

The images also showed a small towing vessel next to the missile, which analysts said indicates the test was conducted from a submersible barge rather than an actual submarine, and that the system was in its early stages.

"The new-type ballistic missile was fired in vertical mode" in the waters off Wonsan Bay, the Korean Central News Agency (KCNA) reported, identifying the weapon as a Pukguksong-3 and saying it "ushered in a new phase in containing the outside forces' threat."

The United Nations Security Council meanwhile is expected to hold closed-door talks early next week on the latest test, diplomats said.

Those talks were requested by Britain, France and Germany, as the European powers push for the world body to keep up pressure on Pyongyang which is under heavy US and UN sanctions over its weapons program.

North Korea is banned from ballistic missile launches by Security Council resolutions.

It is also under three sets of UN sanctions adopted in 2017 in an effort to force it to give up its nuclear and ballistic weapons programmes. They limit North Korea's oil imports and impose bans linked to its exports of coal, fish and textiles.

Since the US-North Korea talks began, Russia and China have been calling for the UN to start lifting sanctions so as to create momentum towards the North's denuclearisation. But the United States has refused.