Secretary of State John F. Kerry and Undersecretary of State Wendy Sherman attend the Iran nuclear talks in Vienna on Friday. (Carlos Barria/Pool photo via AP)

Secretary of State John F. Kerry pressed on with efforts to negotiate a nuclear agreement with Iranian diplomats Saturday as Iran’s supreme leader called the United States “the true embodiment of global arrogance.”

In what could prove to be a decisive weekend in the effort to curb Iran’s nuclear program and lift sanctions against the country, Kerry held back-to-back meetings with his counterparts from Germany, France, Britain, the European Union and Iran. At midday in Vienna, following a meeting with Iranian Foreign Minister Mohammad Javad Zarif, Kerry tweeted that the negotiators “still have difficult issues to resolve.”

The diplomats decided on Friday to extend an interim agreement through Monday, in effect pushing back the deadline for the third time in two weeks of high-level negotiations.

But even as they spoke, on the 15th consecutive day of talks, Iran’s supreme leader, Ayatollah Ali Khamenei, gave a provocative answer when a participant at a meeting of students in Tehran asked what would happen to the “fight against global arrogance” when the nuclear talks end.

“Fighting global arrogance is the core of our revolution, and we cannot put it on hold,” he said, according to remarks posted on his Web site. “Get ready to continue your fight against global arrogance.” Then he added, “The U.S. is the true embodiment of global arrogance.”

Arrogance is a common label in Iran for the United States and its allies in Europe and Israel. The same phrase was used by Ali Jafari, the commander of Iran’s Revolutionary Guard Corps, in an interview published Saturday by the state-run news agency, IRNA. Jafari suggested that Iran will continue to support proxy groups fighting elsewhere in the Middle East.

“God willingly, we are helping all Muslim nations attain dignity and human rights,” he said, adding that people in Iraq, Syria, Yemen, Lebanon and the entity known in Iran as Palestine should be liberated from global arrogance.

Despite the antagonistic words from Tehran, negotiators in Vienna proceeded with what looked like a push to finalize an agreement after a year and half of talks.

French Foreign Minister Laurent Fabius and British Foreign Minister Philip Hammond, who both left the talks on Friday, returned Saturday to rejoin the United States and Germany. The foreign ministers of Russia and China have said they will come back when their presence is needed.

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