TEHRAN (AFP) — Iran on Sunday condemned as “unjustifiable” the reinstatement of United Nations (UN) sanctions over its nuclear program, after the collapse of talks with Western powers and Israeli and US strikes on its nuclear sites.

The measures, which bar dealings linked to the Islamic republic’s nuclear and ballistic missile activities, took effect overnight after Western powers triggered the so-called “snapback” mechanism under the 2015 nuclear accord.

“The reactivation of annulled resolutions is legally baseless and unjustifiable... all countries must refrain from recognizing this illegal situation,” the Iranian foreign ministry said in a statement.

“The Islamic Republic of Iran will firmly defend its national rights and interests, and any action aimed at undermining the rights and interests of its people will face a firm and appropriate response,” it added.

The return of the sanctions ends months of tense diplomacy aimed at reviving nuclear talks derailed since June, when Israeli and US forces bombed Iranian nuclear facilities.

Despite the reimposition, Western leaders stressed channels for dialogue remained open.

US Secretary of State Marco Rubio urged Iran to “accept direct talks, held in good faith.”

He also called on UN member states to “immediately” implement sanctions to “pressure Iran’s leaders to do what is right for their nation, and best for the safety of the world.”

The British, French and German foreign ministers said in a joint statement they would continue to seek “a new diplomatic solution to ensure Iran never gets a nuclear weapon.”

They also called on Tehran “to refrain from any escalatory action.”

Iran had allowed UN inspectors to return to its nuclear sites, but President Masoud Pezeshkian said the US had offered only a short reprieve in return for handing over its whole stockpile of enriched uranium, a proposal he described as unacceptable.

An 11th-hour effort by Iran allies Russia and China to postpone the sanctions until April failed to win enough votes in the Security Council on Friday, leading to the measures taking effect at 3:30 a.m. in Tehran on Sunday.

Germany, which triggered the return of sanctions alongside Britain and France, had “no choice” as Iran was not complying with its obligations, Foreign Minister Johann Wadephul said.