Britons are being warned to be vigilant amid fears of revenge atrocities over Osama bin Laden's shock killing.
Security services were on high alert across the West after predictions of tit-for-tat bloodshed in the coming weeks.
Al-Qa'ida will "undoubtedly" recover and strike back in retaliation, experts said.
The Government urged caution over "inflammatory" warnings from extremists of another 7/7-style terror attack.
Defence Secretary Liam Fox has ordered British military bases to maintain a "high level of vigilance".
But Home Secretary Theresa May said the country's overall threat level from international terrorism remained unchanged at "severe".
Ms May said: "There is a continuing need for everyone to remain vigilant and to report any suspicious activity to the police."
Associates and supporters of bin Laden said the killing will not see an end to al Qaida.
Domestic attacks and "more intense fighting" in Iraq and Afghanistan will be sparked within days, Anjem Choudary, the former UK leader of the outlawed al-Muhajiroun organisation, said.
He said supporters in the UK loved bin Laden "the way they care about their own parents".
Noman Benotman, a former jihadist leader of the Libyan Islamic Fighting Group and an associate of bin Laden from 1989 to 2000, said Bin Laden's death is a "major blow" to al-Qa'ida.
But he added: "At an operational level, bin Laden's death may have no immediate effect on the group's activities."
John Gearson, reader in terrorism studies and director of the Centre for Defence Studies at King's College London, said embassies and military around the world will remain on high alert "for some time".
"I think the significance of what has happened cannot really be overstated," he said.
"There will be concerns that there could be some sort of retaliation, that al-Qa'ida may well want to demonstrate that they are still strong and still in the game."
Frank Faulkner, a terrorism specialist at the University of Derby, said revenge attacks in the aftermath of bin Laden's death were on the horizon, adding: "It's just a case of when and where."
"Every security operation in the world will be on the highest state of alert in readiness for any kind of attack by al-Qa'ida," he said.
Professor Paul Wilkinson, a counter-terrorism expert at St Andrews University, warned there was "no simple military solution" to terrorism.
"You can't beat terrorism on the battlefield alone," he said.
"To expect them to carry the whole burden is quite unrealistic."
While the military had proved very effective in carrying out specialist operations, there was a broader battle to be won, he said.
International efforts to win "young hearts and minds" must continue, he added.
"The creation of a new generation of suicide bombers from young, alienated, angry Muslims would be a very serious blow," said Prof Wilkinson
Second-in-command Ayman al-Zawahiri, who has issued a number of statements on behalf of the terror group, was likely to take over its leadership, "at least in the interim".
A spokesman for the Henry Jackson Society think-tank said Britain "cannot afford to flag in flushing out the remnants of al-Qa'ida and the Taliban in Afghanistan and Pakistan".
Professor Anthony Glees, director of the centre for security and intelligence studies at the University of Buckingham, said the American operation could have been behind the Duke and Duchess of Cambridge's decision to remain in the UK following their wedding.
"The Government would probably have been told that now would not be a good time for the royal couple to travel off to the other side of the world," he said.
But a Palace spokesman said William and his bride had made their decision to stay in the country "weeks ago".
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