Updated at 11:04 a.m. ET
WASHINGTON - President Obama said the U.S. has a "very good estimate" of when Iran could complete work on a nuclear weapon, but cautioned that there are still many unanswered questions about Tehran's inner workings.
"Do we know all of the dynamics inside of Iran? Absolutely not," Mr. Obama said. "Iran itself is a lot more divided now than it was. Knowing who is making decisions at any given time inside of Iran is tough."
Mr. Obama said that while he believes the standoff with Iran over its nuclear program can still be resolved through diplomacy, the U.S. has done extensive planning on a range of options.
"We are prepared to exercise these options should they arise," Mr. Obama said during an interview with NBC that aired Monday on the "Today" show.
On Syria, where human rights groups say government forces have killed hundreds of people over the last few days in an effort to contain an uprising against President Bashar Assad, Mr. Obama said it is important to resolve the ongoing conflict there without outside military intervention.
The president says a negotiated solution in Syria is possible and defended his administration's handling of the violence there, saying the U.S. has been "relentless" in demanding that Assad leave power.
Mr. Obama's comments come amid increased tensions in the Middle East and elsewhere over the prospect that Israel, a key U.S. ally, could soon launch a unilateral strike against Iran. Fearing that such a step could trigger a broader war and disrupt the international economy, the U.S. and other western nations are scrambling to try to persuade Israel against a strike.
On Sunday, Mr. Obama said the U.S. was working in "lockstep" with Israel and did not believe Israel has decided whether to attack Iran, and said he hopes the standoff can be resolved diplomatically.
"I don't think that Israel has made a decision on what they need to do," Mr. Obamawith NBC.
Iran insists its nuclear pursuits are for peaceful civilian purposes, not a bomb.
Iran's regime says it wants to extinguish the Jewish state, and the West accuses it of assembling the material and know-how to build a nuclear bomb. Just last week, Defense Secretary Leon Panetta would not dispute a report that he believes Israel may attack Iran this spring in an attempt to set back its nuclear program.
Mr. Obama refused to say whether the United States would get notice from Israel before any potential strike on Iran.
"I will say that we have closer military and intelligence consultation between our two countries than we've ever had," Mr. Obama said, adding, "We are going to be sure that we work in lockstep as we proceed to try to solve this hopefully diplomatically."
The United States is leading that persuasion initiative, even though Washington largely has concluded that outside argument will have little effect on Israeli decision-making.
"Any kind of additional military activity inside the Gulf is disruptive and has a big effect on us," Mr. Obama said. "It could have a big effect on oil prices. We've still got troops in Afghanistan, which borders Iran."
As for the danger of retaliation by Iran against the United States, Mr. Obama said, "We don't see any evidence that they have those intentions or capabilities right now."
Turning to domestic politics, Mr. Obama bemoaned the role of big money in the presidential race, particularly the influence of political action committees, known as super PACs.
"One of the worries we have in the next campaign is that there are so many of these so-called super PACS, these independent expenditures, that are going to be out there," Mr. Obama said. "There's going to be just a lot of money floating around."
Mr. Obama said he expects many of the ads funded by super PACS to be negative. But he wouldn't say whether he would order his own campaign or ask outside groups supporting him to avoid negative ads.
The president said a successful presidential campaign depends more on convincing the public that you have the right vision for the country than on the strength of your negative ads.