KABUL, Afghanistan (CNN) -- As Gen. Martin Dempsey toured around the globe over the last eight days, one issue was prominent -- Iran's nuclear intentions.
Dempsey, in an exclusive interview with CNN, warned that Iran is playing a dangerous game that could ensnare the Middle East, the United States and others into conflict and a renewed nuclear arms race. From Iraq to Afghanistan, Kuwait to Saudi Arabia, the chairman of the Joint Chiefs of Staff heard about growing concerns about Iran's ambitions.
"My biggest worry is they will miscalculate our resolve," Dempsey said in an interview conducted during a stop in Afghanistan. "Any miscalculation could mean that we are drawn into conflict, and that would be a tragedy for the region and the world."
The recent loss of a U.S. spy drone over Iran exposed part of America's espionage efforts against the country. CNN recently reported that the drone was sent into Iran to conduct surveillance of possible nuclear sites. In perhaps the most candid comments yet from an American official about the spying efforts, Dempsey said the loss of the drone is not the end of U.S. efforts to figure out what Iran is doing.
"If you are asking, 'Are we gathering intelligence against Iran in a variety of means?' the answer is of course," Dempsey said. "It would be rather imprudent of us not to try to understand what a nation who has declared itself to be an adversary of the United States is doing".
Behind the scenes Dempsey is quietly leading the ongoing military planning for an attack against Iran's nuclear weapons in the event the president gives the order to do so.
"We are examining a range of options," Dempsey said, echoing the "all options on the table" line used by administration officials.
Dempsey, the highest-ranking officer in the U.S. military, said the military options are achievable.
"I am satisfied that the options that we are developing are evolving to a point that they would be executable if necessary," he said.
Dempsey said there is no guarantee that Israel will give the United States warning if it decides to attack Iran. But America is sharing intelligence with Israel, Dempsey said.
"We are trying to establish some confidence on the part of the Israelis that we recognize their concerns and are collaborating with them on addressing them," he said.
Other countries are also on edge about Iran's progress toward a nuclear weapon. If Iran gets a nuclear weapon, the Saudis have said they will pursue getting the same capability. Dempsey said the United States believes a nuclear arms race in the Middle East would be a disaster for everyone.
Dempsey's candid comments come as Secretary of Defense Leon Panetta declared the United States believes Iran is capable of developing a nuclear weapon within a year's time, if it chooses to do so.
Panetta told CBS News that "it will probably be a year before they can" have a nuclear bomb but added it could be done in less time "if they have a hidden facility somewhere in Iran." The report also said that according to Panetta there is no indication the Iranians have made the decision to press ahead.
In November, Israel's Defense Minister Ehud Barak told CNN's Fareed Zakaria that Iran is probably less than a year away from being at a point that it will be too late to stop its nuclear program.
"It's true that it wouldn't take three years, probably three quarters, before no one can do anything practically about it because the Iranians are gradually, deliberately entering into what I call a zone of immunity, by widening the redundancy of their plan, making it spread over many more sides," Barak said.
But U.S. intelligence officials have noted in the past that capability and intent are two different matters. Back in February, Director of National Intelligence James Clapper told a Senate committee that while Iran "continues to advance its uranium enrichment capabilities along with what appears to be the scientific, technical and industrial capacity to produce nuclear weapons" it is a question "if its leaders choose to do so."
The Pentagon is pushing back against suggestions that Panetta has speeded up the U.S. prediction of when Iran could have a nuclear weapon.
"Nothing has changed about the views he has expressed -- repeatedly -- of the concerns about where Iran is headed and about the approach the United States and the international community need to continue to take," Pentagon spokesman Capt. John Kirby said Tuesday.
"I think what he meant in general was they could have the nuclear weapons capability in a year, I think was how he captured that," Kirby said. "We all recognize that is a difficult process -- could be that fast, might not be that fast."
CNN's Pam Benson and Charley Keyes contributed to this report