North Korea has warned that it could revive its scrapped policy of building up its nuclear arsenal if the U.S. does not remove harsh economic sanctions as part of reciprocal measures Pyongyang has demanded in ongoing denuclearization talks.

In a statement released Friday, North Korea’s Foreign Ministry said Pyongyang could revert to leader Kim Jong Un’s signature policy of pyongjin, or “parallel advance,” in which the country simultaneously pursues economic and nuclear development.

“If the U.S. keeps behaving arrogant without showing any change in its stand … the DPRK may add one thing to the state line for directing all efforts to the economic construction adopted in April and as a result, the word ‘pyongjin’ (simultaneously conducting economic construction and building up nuclear forces) may appear again and the change of the line could be seriously reconsidered,” the statement said.

In April, Kim abruptly announced he was retiring the policy of pyongjin, which is also known as byungjin. That strategy had been at the center of regime propaganda and is enshrined in the charter of the ruling Workers’ Party. In his April announcement, he also said the North was adopting a “new strategic line” that focuses on rebuilding the country’s tattered economy.

By alluding to a return to its dual-track policy, Pyongyang may be attempting to throw Washington off balance ahead of key talks next week between U.S. Secretary of State Mike Pompeo and a top North Korean official in the United States.

North Korea has repeatedly demanded that the U.S. roll back punishing sanctions and issue a political declaration ending the 1950-53 Korean War, which was halted in an armistice, as “corresponding measures” for what it claims are credible steps toward denuclearization. These steps have included a halt to all nuclear and missile tests as well as the dismantlement of its sole known nuclear site and a key missile-testing facility.

“The U.S. thinks that its oft-repeated ‘sanctions and pressure’ lead to ‘denuclearization.’ We cannot help laughing at such a foolish idea,” said the statement, released under the name of Kwon Jong Gun, director of the Foreign Ministry’s Institute for American Studies.

At a landmark June summit in Singapore, Kim agreed to a vaguely worded 1½-page joint statement to “work towards the complete denuclearization of the Korean Peninsula,” while Trump committed to “provide security guarantees” to the regime.

But negotiations have hit a wall in the wake of that summit.

Media reports after that meeting citing anonymous U.S. intelligence officials have said that the North continues to develop its nuclear program despite its vow to work toward relinquishing its nukes.

Friday’s statement marked the first time that Pyongyang had alluded to potentially resuming weapons tests since the April policy shift. Last year, the North conducted a raft of missile launches — including two over Japan and one of a missile believed capable of striking most of the continental United States. It also conducted its most powerful nuclear test to date.

In the talks, Washington has reportedly demanded that Pyongyang disclose a full inventory of nuclear weapons and fissile materials before any U.S concessions. The North, however, has insisted that the U.S. move first on the war-ending declaration and easing of sanctions as a way of “trust-building” after years of the United States’ “hostile policy” toward it.

“Now that we gave all things possible to the U.S., things it hardly deserves, by taking proactive and good-will measures, what remains to be done is the U.S. corresponding reply,” Friday’s statement said.

“Unless there is any reply, the DPRK will not move even 1 mm, how costly it may be,” it added.