U.S. President Barack Obama said Sunday the just-concluded deal on ridding Syria of its chemical weapons arsenal offers a "lesson" to Iran that it is possible to resolve the U.S.-Iranian nuclear standoff diplomatically.

In an interview with ABC's "This Week With George Stephanopoulos," Obama said both a credible threat of force, combined with a rigorous diplomatic effort, will lead to a deal on solving the crisis over Iran's nuclear program.

The U.S. and Russia reached a deal Saturday in Geneva on placing Syria's chemical weapons under international control and destroying them by mid-2014, so to avert a U.S. military strike on the war-torn Middle Eastern country.

The agreement, reached by U.S. Secretary of State John Kerry and his Russian counterpart Sergei Lavrov, was struck after the Obama administration lobbied intensively Congress for authorizing its use of force against Syria over the latter's alleged chemical attack in the suburbs of Damascus on Aug. 21, which the U.S. claims killed more 1,400 people.

The Obama administration has also threatened to use force to thwart what it suspects Iran's attempt to acquire a nuclear weapon through its controversial nuclear program, which Tehran insists is solely for the purposes of scientific research and civil energy use.

Obama said Iran's nuclear program is "a larger issue" than the chemical weapons issue, because the threat to Israel posed by a nuclear Iran "is much closer to our core interests," and a nuclear arms race in the region would be "profoundly destabilizing."

"And so my suspicion is that the Iranians recognize they shouldn't draw a lesson that we haven't struck to think we won't strike Iran. On the other hand, what... they should draw from this lesson is that there is the potential of resolving these issues diplomatically," Obama said.

Obama revealed that he had communicated with Iran's newly- elected President Hassan Rouhani by exchanging letters, though adding that the negotiations with the Iranians "is always difficult."

"I think this new president is not going to suddenly make it easy. But you know, my view is that if you have both a credible threat of force, combined with a rigorous diplomatic effort..., you can strike a deal," Obama said.?