Iranian President Hassan Rouhani, sworn in for a second term in front of an audience of foreign officials, reiterated on Saturday that his nation will stand by its obligations in an international nuclear deal.

“Iran will never be the first country to start violating” the accord, Rouhani, 68, said in the Iranian parliament, speaking to officials including European Union foreign policy chief Federica Mogherini. “But we will not sit idle in the face of violations” by other countries, he said, adding that his government would “respond in proportionate measure.”

Mogherini’s presence is a clear show of support for the Iranian president, who built his first four years in office on a policy of engagement with western nations, and for the nuclear deal whose fate is increasingly unclear given U.S. President Donald Trump’s opposition and renewed financial penalties.

Iranian officials say new U.S. sanctions that target the nation’s missile program — which wasn’t negotiated as part of the accord — and the Trump administration’s wish to curb international business with Iran go against the deal reached in 2015 between France, Germany, the U.K., U.S., Russia, China and Iran. The accord placed limits on Iran’s nuclear program in exchange for sanctions relief.

In a meeting with Mogherini prior to the ceremony, Foreign Minister Mohammad Javad Zarif said the EU needs to be “alert” to Trump’s efforts “to undermine the deal laying the blame on Iran.” The EU will safeguard the nuclear deal “with determination,” Mogherini said, according to the official Islamic Republic News Agency.

Rouhani was re-elected in May and on Thursday was endorsed by Supreme Leader Ayatollah Ali Khamenei. He has two weeks to present his list of proposed ministers to the parliament.

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