Iran's Supreme Leader Ayatollah Ali Khamenei banned any further negotiations between Iran and the United States October 7, in a blow to moderates hoping to end the two nations' decades-long estrangement.
Khamenei, the highest authority in the Islamic Republic, already said last month there would be no more talks with the United States after the nuclear deal with world powers, but he has not previously declared an outright ban.
His statements directly contradict those of moderate Iranian President Hassan Rohani, who says his government is ready to hold talks with the United States on how to resolve the conflict in Syria, where the two countries back opposing sides.
"Negotiations with the United States open gates to their economic, cultural, political, and security influence. Even during the nuclear negotiations they tried to harm our national interests," Khamenei said in an address to Revolutionary Guard Navy commanders, according to his website.
"Our negotiators were vigilant but the Americans took advantage of a few chances," he said, contending that talking with Americans brings only disadvantages to Iran.
"Through negotiations Americans seek to influence Iran...But there are naive people in Iran who don't understand this," Khamenei told the IRGC commanders, who are directing Iran's military involvement in Syria.
"We are in a critical situation now as the enemies are trying to change the mentality of our officials and our people on the revolution and our national interests," Khamenei said.
“An important part of the activities of the enemy is to change the calculations of officials and to manipulate people’s revolutionary and religious beliefs,” he said. “Young people are the main target, and they must be alert.”
Khamenei often invokes an unspecified "enemy" when talking about the United States and Israel, which he suspects of plotting to overthrow the Islamic Republic.
Khamenei's dark characterization of the U.S. role in forging the nuclear agreement illustrates his sharp divide with Rohani and other moderates, for whom the deal was a major political victory.
Public hopes have been rising that Iranians will enjoy better living standards under the deal as western sanctions are lifted in exchange for curbs on Iran's nuclear activities.
Khamenei's renewed hostility towards the United States is likely to bolster hardline lawmakers seeking the impeachment of Foreign Minister Mohammad Javad Zarif over shaking hands with U.S. President Barack Obama on the sidelines of the United Nations General Assembly last week.
"On and off the record, it was an accident," Zarif said in an interview with the New Yorker October 6.
"It has already cost me at home. But everything I do costs me at home, so this is not an aberration."
With reporting by Reuters and Tehran Times