The war on terror could last up to 50 years, a senior UK intelligence officer has warned.
Security alerts are now a fact of life
Speaking at a US Government sponsored conference in Las Vegas, Superintendent Stuart Harrison offered a rare insight into the intelligence community.
He said "remorseless effort" was needed before the world returned to normal.
Superintendent Harrison, a counter-terrorism expert, was at the conference to share the UK's experiences in dealing with al-Qaeda.
'Bigger than imagined'
Security forces on both sides of the Atlantic have been forced to reassess their way of working following the 11 September terror attacks on the US.
Superintendent Harrison outlined how the UK had reorganised its counter-terrorism efforts in the face of what he described as a new threshold of threat.
"This is bigger than everything we have ever imagined before", he said, "we are in this for the long run. It will be 35 to 50 years before we get it cracked."
Throughout 2003, there was a catalogue of events which highlighted the danger to the UK.
They ranged from the discovery of traces of the toxin ricin in North London to British citizens mounting suicide bombings in Israel.
Underlining the degree of danger, Superintendent Harrison said that there had been 558 arrests in connection with Islamic terrorism in the last year.
As the Counter Terrorist Police Military Liaison Officer for the Association of Chief Police Officers, he has first-hand knowledge of the potential threats against the UK.
In his address to the Vegas conference, he painted an alarming picture of the greatest risks at the moment, such as from shoulder-launched anti-aircraft missiles.
"The threat is very very real," he said. "We are fairly certain there are SAM 7 [anti-aircraft missiles] within the UK with al-Qaeda cells waiting for an opportunity to use them."
Perhaps more worryingly, he also spoke about the likelihood of suicide bombings within the UK.
There were 558 arrests in connection with Islamic terrorism in the last year
"Suicide attacks are inevitable," he said. "We are seeing UK being attacked overseas but it is by no means certain we will avoid an attack for very long."
He added that police had already found belt bombs that had been manufactured in Britain.
On the positive side, he told his American counterparts that the UK was well experienced in dealing with terrorists due to the Northern Ireland troubles.
"Northern Ireland has been the best training ground in peace support operations than any police force has had in the world," he said.
In addition, the UK has responded to the realities of a post 9/11 world by improving coordination between the police, military and intelligence community.
"We set up structures to ensure that the key intelligence could be passed on to those who needed it within an hour."
When there was a threat to the funeral of the Queen Mother, the information was received from Northern Ireland and passed to the officers on the street within 20 minutes.
"We need to understand who we are fighting against, develop our technology and most of all have the people who are skilled at dealing with the threat," said Superintendent Harrison.
The US Government Convention on Emerging Technologies was held in Las Vegas last week to coincide with the Consumer Electronics Show.