TEL AVIV, Israel — With Israel readying a new ground offensive into Lebanon against Hezbollah, the Jewish state’s former deputy prime minister and most vocal advocate for Arab democracy says the time has come for the world to take tough action, including mounting a military strike, against Iran.

In an interview yesterday, Natan Sharansky also expressed concern about Prime Minister Olmert’s hesitance to take the tough action necessary to rid Israel of the Hezbollah threat once and for all. “Even when Israel decides to fight, it still remains hesitant. This decision to only use the air force without a ground force for the first two weeks of the war is not the way to win,” he said.

On the day the U.N. Security Council issued its most ominous threat yet to Iran to abandon its nuclear ambitions, Mr. Sharansky said he believed that sooner or later the world would have to take drastic military action if Iran persisted in building a nuclear weapon.

He said the hesitation of the free world to make common cause with dissidents in the Muslim world is already having consequences, particularly in Iran. “I think it’s unfortunate the free world did not give support to the Iranian opposition. America at times was undermining this opposition,” he said. And while he acknowledged that a strike on Iran’s nuclear infrastructure would have disastrous effects on the Iranian opposition, he also said that at this point, the world did not have much choice but to make the hard decision.

“On the one hand, I know enough that the greater the chances that Iran will be attacked, the easier it will be for the regime to neutralize the opposition and focus the population on an external enemy. This is what dictators always try to do,” he said. “On the other hand, the world cannot afford to have the worst weapons in the hands of a terrorist regime. The world will be blackmailed. This is why the world will have to act. Nonetheless, things will be more difficult for the opposition in Iran.”

Mr. Sharansky is perhaps more influential in Washington these days than he is in Jerusalem. From his Spartan office in the basement of the Knesset, Mr. Sharansky noted that his assessment of the war was mixed. He said he was impressed by the overwhelming public support for the military’s campaign against Hezbollah, but he also worried that the free world is losing its moral clarity.

“In this struggle, the missiles destroyed by us then become propaganda missiles intended to convince the free world to impose restrictions on our campaign,” Mr. Sharansky said, referring to Israel’s attack Sunday on a residential building in Qana that killed 56 civilians. The photos and videos from the aftermath of the strike have unleashed a wave of anger throughout the Arab world, as well as international condemnation. Israel is now investigating the incident, but yesterday said rockets were launched from the area.

“We went to war to restore our deterrence. They have their weapon of deterrence, too, the weapon of public opinion in the free world, which cannot make a distinction between us and the terrorists. We have to stick to our strategic aim, even with all of this pressure.”

He conceded that to a certain extent, Israelis were not taking the world’s condemnation as seriously. He pointed to headlines in British newspapers calling the IDF’s 2002 in the West Bank town of Jenin a massacre. “One British writer called this the worst crime against humanity since the Holocaust. But Jenin was one of the most careful operations, in terms of care for Palestinian civilians, the army ever undertook. We remember these things.” But he also said, “These things have an effect on us, there is no doubt. We are part of the free world; we need the free world’s solidarity.”

For Mr. Sharansky, a survivor of the Soviet gulags, the free world’s solidarity is the key to defeating not only terror, but the authoritarian states that create the conditions for terrorism. His office is adorned with a painting of his mentor and hero, the Soviet dissident and scientist Andrei Sakharov, and the petition the Israeli Knesset signed on his 36th birthday in 1984, when he was still in a Soviet prison camp.

And yet the diminutive former refusenik has run into consistent opposition to his ideas in Israel. There is a joke here that more people have read his book, “The Case for Democracy,” than in Washington in Jerusalem. Even in his own party, Likud, some today dismiss his vision of defeating terrorism by spreading liberalism and democracy to the Arab and Islamic world.

“I read the book and it’s quite good,” a former Likud chairman of the Knesset’s national security committee, Yuval Steinitz, said. “Democracy requires an open society and the Arab societies seem to be far away from this. There must be a cultural reason for this. Maybe there are other reasons for it, too, but there are no Arab democracies. And if you look at the Muslim world, the only democratic exception is Turkey.”

Mr. Sharansky, like President Bush, who has credited his book with influencing his own foreign policy, has rejected this cultural explanation for the lack of democracy in the Arab world. But nonetheless, he said he is not surprised by the lack of support his ideas have received in Israel. He joked that Prime Minister Sharon once told him, before one of his trips to Washington, that he was “going to talk to Bush about things that don’t exist.”

“One of the problems in Israel is that we are dealing with so many immediate problems. This is best summed up in the name of the group Peace Now. Everything is now, we need quick decisions,” he said. “But we need patience and a strategy right. Throughout the free world, there is skepticism about freedom.”