UNITED NATIONS – Prime Minister Benjamin Netanyahu of Israel sought to shred the credibility of Iran's new president Tuesday, using his annual speech at the U.N. to cast him as a beguiling figure who used soothing words and charm to mask intentions to build nuclear weapons.

In remarks interspersed with sarcasm about the new Iranian president, Hassan Rowhani, who visited the U.N. last week and proclaimed that Tehran wanted to reach a peaceful resolution of its protracted nuclear dispute, Netanyahu declared that Rowhani was no different from any other president of Iran since the 1979 Islamic revolution.

"They've all served that same unforgiving creed, that same unforgiving regime," said Netanyahu, who regards Iran as Israel's most potent enemy and its development of a nuclear weapon as an "existential threat." He said "President Rowhani, like the presidents who came before him, is a loyal servant of the regime."

Netanyahu dismissed any thought of allowing Iran to enrich uranium to even a low level, insisting that the only way to ensure that it would never build a nuclear weapon was a complete dismantlement of its capability to enrich nuclear fuel. He exhorted the West to intensify economic sanctions on Iran instead of easing them, as Rowhani has demanded.

"I wish I could believe Rowhani, but I don't," Netanyahu told the General Assembly, where Iran's seats were vacant. "Because facts are stubborn things."

Netanyahu said that nothing in Iran's entreaties for sanctions relief included concessions on its uranium enrichment capabilities. He likened Iran's strategy to that of North Korea's deceptive path to a nuclear weapon and suggested that Iran's behavior resembled that of the fascist dictatorships of history.

"The last century has taught us that when a radical regime with global ambitions gets awesome power, sooner or later its appetite for aggression knows no bounds," he said.

Netanyahu said the international response to Iran's entreaties for sanctions relief should be "distrust, dismantle and verify," and he repeated his warnings that Israel reserved the right to preemptively strike Iran's nuclear facilities if it deemed that the Iranians were close to producing nuclear weapons.

Khodadad Seifi, a deputy ambassador at Iran's Mission to the U.N., rejected the notion that Iran was building a nuclear arsenal and asserted its right to self-defense.