Jerusalem (CNN) -- An Israeli think tank with close links to the government has simulated what would happen in the Mideast and internationally if Israel attacked Iran's nuclear facilities -- and concluded that reaction would be "in the direction of containment and restraint," not the trigger for a larger war.
The Tel Aviv-based Institute for National Security Studies (INSS) says it held a "war game" several weeks ago -- when "it appeared that the fall of 2012 would be a critical period" -- simulating the initial ramifications of Israeli airstrikes on Iran's nuclear facilities.
"This sense of an imminent decision has since abated somewhat, but after the U.S. and Israeli elections, the question of an attack will undoubtedly resurface," the think tank says in a report published this week in its online "INSS Insights."
For its war game, INSS used ex-Israeli diplomats and military officials who played different roles, such as pretending to be the heads of state from Israel, the United States, Russia and Iran, reacting to developments in the first 48 hours after such an attack.
The war game was planned and enacted in September -- the same month that Israeli Prime Minister Benjamin Netanyahu called on the United Nations General Assembly to stop Iran from developing nuclear weapons, holding up a picture of a spherical bomb and drawing a red line below the fuse.
In the Institute for National Security Studies' scenario, Israel informs the United States of its attack plan after its planes are in the air, but the United States later "stood by Israel's side and did not expose its differences in opinion with Israel," the think tank said in its summary of the simulation.
While some analysts predict "the outbreak of World War III" after such an attack, the think tank said the September simulation aimed for a different approach: "containment and restraint."
"The intention was not to predict developments, rather to examine the significance and implications of one possible scenario," the think tank said. "The players acted very rationally, demonstrating preventive policies and motivated by crucial interests alone."
The Israeli Institute for National Security Studies is based at Tel Aviv University and describes itself on its website as an independent, nonpartisan academic institute but adds that it has "a strong association with the political and military establishment" in Israel.
The think tank's analysis of its simulation doesn't go into details about how Barack Obama or Mitt Romney might respond as U.S. president if Israel attacked Iranian nuclear sites.
Iran insists that its nuclear program is for peaceful purposes, but the program came up in last month's final presidential debate between the two candidates.
"As long as I'm president of the United States, Iran will not get a nuclear weapon. I made that clear when I came into office," Obama said.
Romney also said a nuclear-capable Iran was unacceptable, and said he would support tighter sanctions.
"We need to increase pressure time and time again on Iran because anything other than a solution to this ... which stops this nuclear folly of theirs, is unacceptable to America. And of course, a military action is the last resort. It is something one would only consider if all of the other avenues had been tried to their full extent," the Republican presidential candidate said.
Both candidates said the United States would stand by Israel if that country is attacked.
CNN's Michael Schwartz and Catherine Shoichet contributed to this report.