North Korea says there is no way the United States will bring alternative plans for their stalled nuclear talks to a meeting proposed by Stockholm in two weeks after weekend negotiations in Sweden broke down.

The working-level talks between US and North Korean envoys were broken off on Saturday. The US State Department said it had accepted Sweden’s invitation to return for more discussions with Pyongyang in two weeks.

North Korea said the ball was now in Washington’s court and warned Washington that it would wait only until the end of the year for the United States to change course.

“We have no intention to hold such sickening negotiations as happened this time in Sweden before the US takes a substantial step to make complete and irreversible withdrawal of the hostile policy toward the DPRK,” KCNA state news agency cited a spokesperson for North Korea’s foreign ministry as saying, referring to the official name of North Korea.

Ann Linde, Sweden’s minister for foreign affairs, said the talks had been constructive “for as long as they lasted.”

“Then I think there was a somewhat different view on what to accomplish at one meeting,” she told Sweden’s public broadcaster SVT, adding that Sweden was at the countries’ disposal if they decide to meet again.

“If that is in two weeks or two months remains to be seen. I think it is possible to achieve more talks but that is entirely up to both parties,” she said.

It is unclear whether North Korea will return to the talks but Pyongyang could be using its strategy of negotiating on the edge to gain concessions as fringe benefits of participating in negotiations, experts say.

“They want to create the impression that the cause of the impasse is the inflexibility of the US side and they likely want to force the United States to either come back with a more favorable negotiating position or eventually force President Trump to engage at the summit level to keep diplomacy alive,”said Mintaro Oba, a former US State Department official specializing in the Koreas.

Vipin Narang, a nuclear affairs expert at the Massachusetts Institute of Technology, added that North Korea is also buying time to continue to expand and improve its missile and nuclear force, and negotiate the terms by which it is accepted as a nuclear weapons power.

“If that’s the case, their best strategy is to dangle the hope of a fictional future deal but stall on actual negotiations, let alone crafting or implementing any such deal,”Narang said.

Under sanctions banning much of its trade because of its weapons program, North Korea recently test-fired a new ballistic missile designed for submarine launch, a provocative gesture that also underscored the need for Washington to move quickly to negotiate limits on Pyongyang’s growing arsenal.