Three different groups have claimed responsibility for the bombings last week at the Egyptian resort of Sharm el-Sheik. Authorities in Cairo and London are wondering whether the bombings in Egypt and the recent attacks in London might be linked, but no connection has yet been established. Islamic radicals harbor resentments against Egypt as well as Britain.

Evan Kohlmann, a terrorism consultant and author of "Al-Qaida's Jihad in Europe," urges against jumping to conclusions that the same group ordered both bombings, although the coincidences, he says, are strong.

"I suggest that it may be a little bit too early to draw firm conclusions, but it seems a little bit of a strong coincidence that these two events would have happened so close together, both involving Pakistani nationals. It's the kind of coincidence that usually proves to be a connection," he said.

But, 10 years ago terrorists blew up a federal building in Oklahoma City, Oklahoma in what was until 2001 the worst act of terrorism on U.S. soil. Commentators immediately placed the blame on Islamic radicals. The culprits turned out to be right-wing American extremists.

Don Hamilton, acting director of the National Memorial Institute for the Prevention of Terrorism, a government-funded research organization in Oklahoma City, also cautions against drawing premature conclusions. But he notes that al-Qaida attacks have come in waves.

"Al-Qaida has always done things in sort of waves - that is, they're not a steady drumbeat kind of an organization, with the exception of al-Qaida in Iraq, where you have a very different kind of dynamic in a country in the midst of a war with a major insurgency intertwined with it," he said.

But why attack Egypt, which is a Muslim country? Analysts note that al-Qaida is opposed to governments in Egypt and Saudi Arabia for being insufficiently Islamic in nature. So, attacking high-scale resorts is a blow to tourism, a big source of income in Egypt.

Mr. Kohlmann says the clue to an al-Qaida link in the Egyptian bombings comes from Iraq. He notes that Abu Musab al-Zarqawi, thought to be the head of al-Qaida in Iraq, released a videotape of al-Qaida's interrogation of the Egyptian ambassador to Iraq, whom the terrorists captured and later killed.

"The same day as the Sharm el-Sheik bombings, Zarqawi's al-Qaida faction in Iraq released a video of the interrogation of the former Egyptian ambassador to Baghdad who was recently killed by Zarqawi. And in this interrogation, the ambassador is specifically asked about Jewish presence in the Sinai. And he's asked, which areas of the Sinai peninsula in Egypt, which are, you know, labeled as Muslim land, in which are there Jews. And what does he say? His response is, from Taba to Sharm el-Sheik," he said.

A series of coordinated bombings last year at Taba, another popular Egyptian resort, killed 34 people, including Israeli tourists.

But analysts say any direct coordination between the Egyptian and British bombers is unlikely because of al-Qaida's structure - or, perhaps, the lack of one. Many terrorism experts now lean to the theory that al-Qaida is not a top-to-bottom organization taking orders from a central authority, but is rather a grouping of scattered cells with a great deal of operational autonomy. Analyst Don Hamilton calls this concept "leaderless resistance," and he says it was used by U.S. right-wing groups to avoid government surveillance.

"You'd make yourself a part of a common cause but you wouldn't report to anyone. The logic is, good law enforcement and intelligence agencies can penetrate command and control systems. But if there is no command and control system, there's nothing to penetrate," he said.

But experts do not discount that attacks may be launched by groups that have no affiliation or loyalty to al-Qaida, but are nevertheless sympathetic to their brand of Islamic radicalism.