Iran has reportedly arrested (and/or kidnapped) opposition leaders Mir Hossein Mousavi and Mehdi Karroubi in an apparent bid to discourage the sort of mass protests shaking the Arab world from unfolding in Iran.

Mousavi and Karroubi had been confined to their homes since pro-reform demonstrators took to the streets on Feb. 14, and more protests are still planned for Tuesday.

Will detaining Mousavi and Karroubi help Iran stamp out an uprising before it happens, or merely fuel calls for change? Opinion and analysis here.

Of all the Arab nations swept up in the post-Tunisia domino wave of anti-government protests, Bahrain may pose the biggest threat to the U.S. The tiny Persian Gulf island kingdom houses the U.S. Navy’s 5th Fleet and an Air Force base, a toehold the U.S. relies on to contain neighboring Iran. The Bahrain base also allows the U.S. to keep tabs on the 40 percent of the world’s oil that passes through the Strait of Hormuz. Bahrain’s protesters are mostly Shiite Muslims, as in Iran. If they overthrow the Sunni royal family and force the U.S. out, will Iran gain the upper hand in the region? Some opinion: 

• This is about Bahrain, not Iran: The U.S. media is framing this as a Sunni-Shiite battle, and we all know, at least vaguely, by now that “Shiites have something to do with Iran,” says Aaron Bady in Zunguzungu. But a closer look suggests this is class warfare — the haves, mostly Sunni, versus the largely Shiite have-nots — not a “sectarian conflict.” Besides, these protests have been going on for “quite some time.” We’re just finally noticing them now.

More opinion within.

The wave of popular uprisings in North Africa and the Middle East has already swept Egypt’s Hosni Mubarak and Tunisia’s Zine el Abidine Ben Ali from power. Now, everyone from Western leaders to Arab protesters to nervous autocrats across the Muslim world are wondering: Who’s next? Some possibilities:

• BAHRAIN: King Hamad bin Isa al-Khalifa
  Protesters held an Egypt-style “day of rage” on Monday, and the “deep grievances” of the country’s poorer Shia Muslim minority make Bahrain “the most susceptible” of the Gulf states to popular revolt, says regional analyst Theodore Karasik, as quoted by Bloomberg Businessweek. King Hamad, part of the Sunni elite, tried to “bribe” each family in the country with thousands of dollars, but that may not be enough to pacify the protesters, says Ditz in Antiwar.com. Bahrain is “the biggest wild-card” in the region.

• IRAN: President Mahmoud Ahmadinejad
  Mubarak’s fall has reinvigorated the passions that fueled the 2009 “Green Revolution,” which went largely underground after harsh government crackdowns. Thousands defied government warnings Monday and took to the streets in Tehran and other big cities, ostensibly in solidarity with Egyptians, but also shouting “death to the dictator.” The chance a full-scale uprising is “moderate,” says Mahanta in Mother Jones, but the odds of another crackdown are “tragically high.”

• PALESTINE: President Mahmoud Abbas
  The day after Mubarak fell, Abbas and the ruling Fatah party scheduled long-overdue national elections for September, and on Monday the entire cabinet resigned. This shows that Abbas is “freaking out,” says Khaled Abu Toameh in The Jersusalm Post. “In the eyes of many Palestinians, Abbas is not much different from Hosni Mubarak,” and these acts of “desperation” are an attempt to keep Egypt’s “anti-government wave” from washing him out of power.

Also, Algeria and Yemen. Read more here.

Iran acknowledged that computers in its nuclear power facilities have been infected with a mysterious and highly sophisticated worm known as Stuxnet. The worm has spread all over the world, even to the U.S., says John Markoff in The New York Times. And now that it’s everywhere, governments and hackers are racing to figure out ways to co-opt the powerful worm for their own ends. The people in charge of safety at power plants and dams worldwide “are scared to death,” says former U.S. cybersecurity coordinator Melissa Hathaway. “We have about 90 days to fix this before some hacker begins using it.”