Threats of a possible “Mumbai-style” terror attack on Western interests in Europe are considered “credible” and U.S. officials aren’t ruling out the possibility that the plot could extend to the U.S., a senior U.S. counterterrorism official told NBC News.
The official, who spoke on condition of anonymity, said information about a possible plot emanating from al-Qaida-linked groups in northwest Pakistan was first picked up by U.S. intelligence several weeks ago and was believed to be aimed at targets in France, Germany or the United Kingdom.
But the conflicting nature of the information left open many questions about the seriousness of the plot, U.S. officials said.
One coalition official with access to intelligence reporting told NBC that s ome reports, which came from human sources as well as electronic intercepts, suggested possible attacks on hotels or other public gathering spots in a “fedayeen-style" commando attack by at least 25 operatives, much like the devastating coordinated assault in Mumbai in 2008.
"They were going to attack multiple centers in Europe over a few days," said the official, who also spoke on condition of anonymity. "They were going to shoot the hell out of people, terrorize them."
But a senior U.S. counterterrorism official cautioned that only some of the intelligence involved simultaneous attacks in multiple European cities and said he had no confirmation of the number of operatives who supposedly were involved.Video: Security officials ‘taking threats very seriously’
The officials also gave conflicting accounts on whether Pakistani authorities had made arrests in response to the intelligence.
They agreed on one point, however: T here is no evidence the alleged plot has been disrupted.
"No one is assuming the threat has subsided," the U.S. official said.
U.S. intelligence analysts are divided over how alarming the current threat reporting is and some officials emphasized they have no "specific" information to suggest an attack is imminent — or that the U.S. is being targeted.
Still, the first senior U.S. counterterrorism official told NBC that there is "significant concern" that al-Qaida-linked terrorists based in Pakistan have already activated such a plot. That official and some others indicated that they view the threat more serious than any in the past few years — and can’t rule out that it may involve an attack inside the U.S.
‘The threat is credible’
"Look the threat is credible," the official said, adding that while there is no "specific" information, U.S. intelligence reporting suggests plot planning has gone beyond the "aspirational" phase. "There hasn’t been this level of concern for some time," the official said.
The Wall Street Journal also reported Wednesday that investigators are examining whether the purported plot extended to the U.S.
But another senior U.S. official told NBC News early Wednesday that intelligence officials have found "no U.S. dimension" to the alleged terror plot.
Threat warnings have been building for the past few weeks and briefed to the highest levels of the White House. Partially in response, the CIA has dramatically escalated its drone attacks on al-Qaida-linked militants in northwest Pakistan in recent weeks in an effort to disrupt any plot, the first U.S. official said. There have been 21 drone strikes in Pakistan in September, the highest number ever in a month. The escalation is partly due to the CIA trying to make up lost ground after a sudden drop off in drone attacks during the early part of August due to the flooding in Pakistan. But the agency is also targeting some of the same militant groups believed to be behind the current threats.
"It’s fair to say a lot of effort is being applied" to disrupting any plot, the official said.
At least some of the information on the threat came from a German Islamic militant arrested recently in Afghanistan and now in custody. Germany's Der Spiegel newspaper reported that the suspect lived in Hamburg, Germany, until March 2009, and reportedly had previously worked as cleaner aboard aircraft there.
Other news organizations have reported increased concern about possible attacks in Europe.
Britain’s Sky News reported Tuesday that militants based in Pakistan were planning simultaneous strikes in London, as well as cities in France and Germany.
Sky News said the plot was at an "advanced but not imminent stage."
It said the planned attacks were patterned after the commando-style raids carried out in Mumbai by Pakistan-based gunmen in 2008, when heavily armed militants attacked various targets in the city, including the Taj Mahal hotel and the city's main train station.
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Earlier this month, U.S. officials said that groups and individuals inspired by al-Qaida were switching to smaller-scale attacks that are easier to plan and carry out like the Mumbai attack, NBC News reported. The plots involve fewer people and come together more quickly, the report said.
Four U.S. security officials, who asked for anonymity when discussing sensitive information, told Reuters that initial intelligence reports about the European threat first surfaced roughly two weeks ago, around the time of the anniversary of the Sept. 11, 2001, attacks.
Security officials in France have been put on alert for possible terror attacks. The French parliament voted this month to ban burqa-style Islamic veils in France, a subject that has prompted warnings by al-Qaida’s North African branch, al-Qaida in the Islamic Maghreb, or AQIM. Counterterrorism officials say that is just one of several factors contributing to the heightened threat.
On Tuesday, the Eiffel Tower was briefly evacuated due to a bomb threat called in from a telephone booth. It was the second such alert at the monument in two weeks.
British officials, too, have been aware of a possible attack but the country's terror threat warning has not changed from "severe" — the second highest level in the five-tier system.
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"There have been a succession of terror operations we've been dealing with over recent weeks but one to two that have preoccupied us," one British government official who spoke on condition of anonymity due to the sensitive nature of his work, told The Associated Press. "Still, it hasn't been to the degree that we have raised the threat level."
Another British official, who spoke on the same terms, would not confirm the plot was "al-Qaida inspired" but said there was an "Islamist connection" and that the plots were in an early stage. No other details were given.
German officials also said there had been no change to the country's threat level.
The Associated Press, Reuters, NBC News' Michael Isikoff and Robert Windrem and msnbc.com staff contributed to this report.