World pressure kept Iran from gaining nuclear weapons in the past, and is preventing it from crossing the nuclear threshold now, Prime Minister Binyamin Netanyahu said Tuesday in response to Iranian President Hassan Rouhani's comment that threats against Iran do not work.

The US State Department also responded to Rouhani's remarks, stating that they seek to see "credible steps taken" to address their concerns that a nuclear program that Tehran says is purely for peaceful needs is actually an effort to build a nuclear bomb.

"Iran's president said that pressure won't work. Not true," Netanyahu said during a meeting with 36 Democratic US Congressman in his office. "The only thing that has worked in the last two decades is pressure. And the only thing that will work now is increased pressure," he said.

He added that it was "important to understand" that if the pressure on the Islamic Republic was relaxed "they will go all the way." In a certain sense, Netanyahu was preaching to the converted since the House voted last week – on the eve of Rouhani's inauguration on Sunday – to increase US sanctions on Iran, targeting what remains of its oil sector.

Netanyahu's comments came just after Rouhani gave his first press conference since taking office on Sunday, saying he was "seriously determined" to resolve a dispute with the West over Teheran's nuclear program and was ready to enter "serious and substantive" negotiations on the issue.

But, he said, the other side should realize a solution could be reached "solely through talks, not threats". He said he was confident the concerns of both sides could be removed in a short time.

Meanwhile, the State Department said on Tuesday that the inauguration of Iranian President Hassan Rouhani is a chance for that country to move quickly to resolve concerns about its nuclear program, but the United States wants to see actions from Tehran.

The inauguration of Rouhani, who took his oath on Sunday, "presents an opportunity for Iran to act quickly to resolve the international community's deep concerns over their nuclear program," said State Department spokeswoman Jen Psaki.

She added, however, "there are steps they need to take to meet their international obligations and find a peaceful solution to this issue, and the ball is in their court."

Psaki said, "we want to see credible steps taken" to address concerns that a nuclear program that Tehran says is purely for peaceful needs is actually an effort to build a nuclear bomb.

The United States has said it would be a "willing partner" if Iran was serious about finding a peaceful solution to the issue.

Rouhani, however, turned that equation around, and said that if Washington demonstrated goodwill towards Iran and an atmosphere of mutual respect was created, the way was open for talks to remove the concerns of both sides.

Netanyahu has consistently warned since Rouhani's election in June that the world should not be "taken in" by his perceived "moderation" and let the new Iranian president draw out negotiations as a stalling tactic, all the while continuing full-speed ahead on the nuclear program.

The congressmen who met with Netanyahu are here on a one-week tour sponsored by the American Israel Education Foundation, a charitable organization affiliated with the American Israel Public Affairs Committee. The group, which includes 31 freshman representatives, is led by Democratic Whip Steny Hoyer (D-Maryland). One government official said Iran has already, since Rouhani's election, upgraded its centrifuge capabilities, both by adding "thousands of new centrifuges" and introducing more advanced centrifuges that allows them to dramatically "accelerate their enrichment process."

In recent weeks, the official said, the Iranians have "improved their centrifuges both quantitatively and qualitatively." Alongside efforts to create the material for a bomb through uranium enrichment, Iran was at the same time also working at its Arak heavy water plant on a parallel path to build a bomb based on plutonium.

"They are determined to get a bomb one way or another," he said, adding that the world needed to be equally determined to prevent them from doing so.

Defense Secretary Chuck Hagel, meanwhile, met with Azerbaijan's Defense Minister Safar Abiyev on Monday, telling him that Iran, Azerbaijan's southern neighbor, was running out of time to resolve concerns over its nuclear program diplomatically.

Officials said Hagel, in concert with his counterparts at the State Department and the White House, expected "quick" and meaningful overtures from the Rouhani government.

"Secretary Hagel made clear to the Azerbaijanis that when it comes to Iran ending its nuclear ambitions, time is of the essence," a US official said. "The Iranian election provides an opportunity for further dialogue, but the international community is not going to wait around forever to see concrete steps." A senior US official, meanwhile, was quoted on Israel Radio Tuesday as casting doubts on US intentions to keep Iran from acquiring nuclear arms.

American conduct regarding Syria, contrary to declarations by US President Barack Obama, showed Israel that it could not rely on US assurances, the source was quoted as saying. .

According to the source, Israel was capable of carrying out a unilateral military strike against Iran's nuclear facilities without operational support from the United States. He acknowledged, however that such a strike would be less effective than one conducted by the US.

Sources in the Prime Minister's Office denied that this sentiment mirrored government's position, saying it reflected only the opinion of the source quoted.

Michael Wilner in Washington, Jerusalem Post Staff and Reuters contributed to this report.

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