WASHINGTON -- Storm clouds darkening over the Middle East suggest a growing peril for the United States and the possibility of a new war that could embroil the U.S., Israel, Iran and others in a bloody, costly fight.
Behind this week's exchange of threats between Iran and the United States over access to the Persian Gulf, seasoned analysts see a perfect storm of factors that could trigger armed conflict.
Iran's work on nuclear weapons is fast approaching a "red line," the crossing of which both the United States and Israel say is unacceptable and may have to be halted by force. Washington and European capitals are preparing new sanctions that would sever Iran from the international banking system, a move that would cripple its economy and that Tehran has said it would consider a provocation to war. Growing violence in Syria threatens to spill over its borders with Israel, Lebanon and Turkey, a NATO ally.
Amid the saber-rattling rhetoric from Washington and Tehran, and Arab world upheaval from Egypt to Iraq to Yemen, the United States is planning an unprecedented escalation of military cooperation with Israel, including massive joint exercises this spring to practice joint command and maneuver of ground forces in combat.
And political campaigns, including a struggle between bitterly opposed factions in Iran's March parliamentary elections and the U.S. presidential contest culminating in the fall, are likely to keep all these tensions at a boil.
"'Powder keg' doesn't begin to describe it," said Louise Arbour, president of the International Crisis Group, an independent organization that monitors global tensions. "Rising strategic stakes have heightened the regional and wider international competition," she wrote in a new assessment. It is, she concluded, "an explosive mix."
U.S. Defense Secretary Leon Panetta said last month that the planned maneuvers with Israel, dubbed Austere Challenge, will be "the largest joint exercise in the history" of U.S.-Israeli relations. What had been a biannual series of command-post computer training with simulated forces held in Germany has been expanded this year to Israel and will include U.S. Army combat troops on the ground in Israel, commanded and maneuvered by joint U.S.-Israeli command centers in Europe and Israel.
The joint maneuvers are part of what Panetta has called "unprecedented defense cooperation" with Israel, which also includes joint naval exercises and the training of U.S. Marines on counterterror and urban warfare operations with Israeli commandos.
Austere Challenge will play out in May, shortly after a massive joint missile defense exercise, Juniper Cobra, that will involve U.S. and Israeli defense systems and missile interceptors.
U.S. officials in Washington and Europe declined to provide details on the joint exercises. Air Force Capt. John Ross, a spokesman for the U.S. European Command, which will conduct Austere Challenge, said the exercise "is not in response to any real-world event."
But Iran's work on its nuclear weapons, newly documented last month by the inspectors of the International Atomic Energy Agency, is driving events at a fast clip. Panetta has said Iran could have a nuclear bomb in "about a year ... perhaps a little less" if Iran, as suspected, has a secret uranium enriching facility.
Should Iran cross that "red line," Panetta told CBS News on Dec. 19, "we will take whatever steps necessary to stop it."
The Obama administration and others have tried economic sanctions to drive Iran to abandon its nuclear program. According to a recent report by the Congressional Research Service, the extensive web of international sanctions against Iran is not having an appreciable impact on its economy, which is growing at an enviable 3.5 percent annual rate. But Iran's economy -- and particularly its state-subsidized imports of food and gasoline -- depends on unfettered access to global financial markets.
Legislation reluctantly signed into law by President Barack Obama last week requires the president within 180 days to impose sanctions on any foreign financial institutions that deal with Iran's central bank. Widespread refusal to deal with Iran's central bank would strangle the country's access to hard currency from its oil revenues, which earn Iran, as the world's fourth-largest oil exporter, about $75 billion a year.
In response, Iran has threatened to close the Persian Gulf at its chokepoint, the Strait of Hormuz, through which pass some two dozen giant oil tankers a day carrying one-third of the world's oil consumption.
Although the president can waive the new sanctions for 120 days at a time, a White House spokesman said the administration is working with its European allies and others "to be in a position to most effectively implement" the sanctions, seeking to "avoid negative repercussions to international oil markets."
In anticipation of an oil trade war -- or worse -- oil prices have risen sharply this week, and Iran's currency, the rial, briefly fell to a new low in a signal of rising consumer prices for food and fuel.
The risk, of course, is that the heated rhetoric and implied threats gain a momentum of their own. "As these things go forward it's more difficult to step back," said Michael Adler, an Iran scholar at the Woodrow Wilson International Center in Washington. Speaking of the region as a whole, he added, "It's a tinderbox squared or cubed."
The unintended danger arising from the threatened sanctions is that they might push the U.S. and Iran toward conflict rather than toward a peaceful conclusion, warned Vali Nasr, a senior fellow at the Brookings Institution, a Washington think tank. "This is a significant escalation of tension between the United States and Iran, and the start of a more dangerous phase in the West's attempt to curtail Iran's nuclear program," he wrote in a new analysis.
"War between the U.S. and Iran may very well start, not if and when Washington decides to strike against Iran's nuclear facilities, but because sanctions designed as the alternative to military action end up hastening its advent," Nasr wrote.