Tehran and Washington remained deadlocked on Sunday over the structure of their ongoing nuclear diplomacy, with Iranian officials publicly stating that no timeline exists for a next round of talks unless the United States presents a binding written framework. The standoff marks a significant hardening of Iran's position following weeks of indirect dialogue conducted through Omani intermediaries.

Iranian Foreign Ministry spokesman Esmail Baghaei reiterated on Monday that Tehran would not agree to further meetings 'for the sake of appearances,' insisting that concrete guarantees on sanctions relief and enrichment rights must be codified before any senior-level engagement resumes. The statement came as US special envoy Steve Witkoff was reported to be in consultation with European partners over how to respond to Iran's conditions.

European Union foreign policy officials in Brussels expressed concern that the impasse could derail progress made in earlier sessions, with EU High Representative Kaja Kallas urging both sides to return to the table without preconditions. British, French, and German diplomats — the so-called E3 — are expected to hold a joint call Monday to coordinate their response to Tehran's latest demands.

Analysts note that Iran's insistence on a framework agreement before further talks reflects domestic political pressures, with hardline factions in Tehran opposing any deal that does not explicitly preserve Iran's right to enrich uranium at higher levels. The International Atomic Energy Agency has separately confirmed that Iranian centrifuge operations at Fordow continue at elevated capacity, adding urgency to Western calls for a return to diplomacy.

The White House offered a measured response, with a spokesperson saying the administration 'remains committed to a diplomatic resolution' but stopping short of accepting Iran's preconditions. Observers suggest the next 72 hours will be critical in determining whether a new round of talks can be scheduled before Iran's domestic political calendar further constrains its negotiating flexibility.