Sanctions against Iran are beginning to have more of an impact, CIA Director David Petraeus said on Tuesday.

"The sanctions have been biting much, much more literally in recent weeks than they have until this time," he said at a Senate intelligence committee hearing.

"What we have to see now is how does that play out, what is the level of popular discontent inside Iran, does that influence the strategic decision making of the Supreme Leader and the regime, keeping in mind that the regime's paramount goal in all that they do is their regime survival," Petraeus said.

The CIA chief also said that Saudi Arabia appears to be "ramping up" its oil production and can fill some of the demand shortfalls caused by the sanctions on Iran.

China has reduced its imports of Iranian oil and "it remains to be seen whether that continues. It appears that Saudi Arabian production is ramping up and can fill some of the demand that might have been met by Iranian exports now that there are the sanctions on the Central Bank of Iran," Petraeus said.

Earlier in the hearing, US Director of National Intelligence James Clapper said Iran is keeping the option open to develop a nuclear weapon but US intelligence agencies do not know whether it will eventually decide to build one.

New US sanctions imposed over Iran's nuclear program were likely to have a greater impact than previous ones, but were not expected to lead to the downfall of Tehran's leadership, Clapper told the Senate committee.

"We assess Iran is keeping open the option to develop nuclear weapons, in part by developing various nuclear capabilities that better position it to produce such weapons, should it choose to do so," Clapper said. "We do not know, however, if Iran will eventually decide to build nuclear weapons."

Iran is expanding its uranium enrichment capabilities, which can be used for either civil or weapons purposes, he said.

"Iran's technical advancement, particularly in uranium enrichment, strengthens our assessment that Iran has the scientific, technical, and industrial capacity to eventually produce nuclear weapons, making the central issue its political will to do so," Clapper said.

"These advancements contribute to our judgment that Iran is technically capable of producing enough highly enriched uranium for a weapon, if it so chooses," he said.

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