Why did al-Qaeda attack us on 9/11? Quite simple, said George Bush in 2001: "They hate our freedoms." Not so, responded Osama Bin Laden: "Let him tell us why we did not strike Sweden." Although Sweden may be off-limits for jihadists, the same cannot be said for Sweden's neighbor, Norway.

Last Thursday, three men were arrested in Norway and Germany for allegedly plotting a terrorist attack involving peroxide explosives. Those arrested were all Muslim immigrants to Norway, originally from China, Iraq, and Uzbekistan. Authorities claim that the suspects had links to al-Qaeda in Pakistan, and that one of them visited Waziristan in 2008. If this is true, an al-Qaeda cell had set up shop in the suburbs of Oslo.

Why on Earth would Norway be a target for attack? The country is famed as an international peace negotiator, the home of the Nobel Peace Prize, and the distributor of more foreign aid per capita than any other country. It's an all-round international good guy -- so long as we aren't talking about whaling.

To be sure, no confirmed details have emerged so far about the suspects' motives or their objectives. However, leaks from the investigation suggest that Norway was indeed the target and not a logistics base for an attack elsewhere.

There are several theories about why Norway would be on al-Qaeda's hit-list -- but they raise more questions than answers.

The first explanation is Afghanistan. Norway has been part of the International Security Assistance Force (ISAF) in Afghanistan from its foundation in late 2001. Since Norway threw in its lot with the "crusaders," it's fair game in the eyes of many Islamists. In late 2007, for example, Ayman al-Zawahiri, al-Qaeda's second-in-command, said that the group had previously threatened Norway because it "participated in the war against the Muslims."

But Norway is, at best, a secondary player in Afghanistan. Most of its soldiers are in the northern cities of Meymaneh and Mazar-e-Sharif, a relatively quiet part of the country. And its contingent of 500 personnel is only the 18th largest in the ISAF coalition. Several countries with a bigger troop presence, such as Bulgaria (525), Georgia (925), or Romania (1,140) have so far not been targeted by al-Qaeda. Besides, why attack Norway now, almost a decade after its entry into Afghanistan?

While Afghanistan is likely a factor, then, it's not a satisfactory explanation. So a second theory has been proposed: the cartoon crisis. In early 2006, a small Norwegian newspaper angered many Muslims by reprinting Danish cartoons depicting the Prophet Muhammad. This sparked a flurry of Internet threats as well as physical attacks on Norwegian interests abroad. In Syria, angry demonstrators burnt down the Norwegian embassy. In Pakistan, offices of the Norwegian company Telenor came under attack

Is this the answer? Not necessarily. Once the dust settled in 2006, Norway's role in the cartoon affair was largely forgotten as Muslim fury focused on Denmark. With the exception of a May 2006 threat to Norway from al-Qaeda ideologue Abu Yahya al-Libi, al-Qaeda's leaders have not explicitly linked Norway to the cartoon issue in their statements.

Which brings us to the third theory: Norway's treatment of the Iraqi Kurdish Islamist Mulla Krekar . Onetime leader of the Islamist guerrilla group Ansar al-Islam, Mulla Krekar came to Norway as a refugee in the early 1990s and spent years secretly shuttling between Oslo and Kurdistan until his arrest in September 2002. Although terrorism charges were dropped in 2003, he has been officially declared a threat to national security and placed under house arrest awaiting deportation to Iraq. For many Islamists, Mulla Krekar's treatment demonstrates Norway's subservience to the cruel whims of the United States.

But there is little or no evidence that al-Qaeda cares enough about Mulla Krekar to seek vengeance. He was never part of Bin Laden's organization, and his fate hardly stands out in the post-9/11 world, with its Guantanamos and CIA "black sites."

It may be pointless to search for a single grievance to explain the recent plot. Most likely, a combination of factors placed Norway on the jihadists' radar. In al-Qaeda's binary worldview, Norway is part of the "Jewish-Crusader alliance." Not a platinum member, perhaps, but a member nonetheless. If you're not with al-Qaeda, you're with the United States.

Norway has long been considered a legitimate but low-priority target. Frustrated by the difficulty of striking key adversaries like Britain and the United States, al-Qaeda seems to be moving down the food chain.

Whatever the motivation behind the alleged Oslo plot, the implication is that no country is safe anymore. Except Sweden, of course.