Iran has rejected an opportunity to discuss the future of a nuclear deal with the United States, keeping both nations on a confrontational path instead of a diplomatic one.

On February 18, Washington accepted an offer to hold informal talks with Tehran brokered by the European Union. The goal was for both sides to negotiate a way forward so the US could reenter the multinational pact that limited Iran’s nuclear program in exchange for sanctions relief the Trump administration left in 2018. After that exit, Iran pressured America to lift those penalties by, among other things, enriching uranium above agreed-to levels in the accord.

Now, the Trump administration has been replaced by Biden’s, which wants to reenter the deal. But efforts to do that have reached a stalemate: Iran wants reimposed sanctions on it lifted before welcoming America back into the fold, and the US pushes for Tehran to comply with the accord’s limitations on its nuclear development.

Iran had said it was “considering” the offer to meet, signaling EU-brokered negotiations were mere days or weeks away. But that “maybe” turned into a “no” on Sunday, a troubling indicator that the diplomatic path won’t be straightforward.

The “time isn’t ripe for the proposed informal meeting,” Saeed Khatibzadeh, the spokesperson for Iran’s Foreign Ministry, tweeted on Sunday.

The Wall Street Journal, which first reported Tehran’s decision, noted Iran doesn’t want to meet with the US until it’s clear it would get sanctions relief from such a meeting. Instead, the Islamic Republic wants the EU to mediate a “step-by-step process” whereby both Washington and Tehran offer concessions before any talks.

A White House spokesperson noted the Biden administration is “disappointed at Iran’s response,” but added, “We remain ready to reengage in meaningful diplomacy to achieve a mutual return to compliance” with the nuclear deal.

Keeping chances for diplomacy alive, however, is easier said than done.