A MAMMOTH security operation will be taking place at Champions League games this week - with armed cops stationed on roofs and packs of prowling bomb dogs, security experts warned.
Europe is on high alert after the Islamic State death cult vowed to "kill them all" in a disturbing threat that singled out quarter final matches in London, Madrid and Paris.
Arsenal host Bayern Munich tonight as Manchester City travel to face Real Madrid, while tomorrow Atletico Madrid take on Borussia Dortmund and Paris Saint-Germain host Barcelona.
But last night, ISIS released a warped propaganda poster claiming they were ready to launch attacks at Arsenal's Emirates Stadium, Real's Santiago Bernabeu, Atletico's Metropolitano Stadium and PSG's Parc de Princes.
It comes amid fears ISIS is rising again after an Afghanistan-based splinter cell known as ISIS-K claimed responsibility for the Moscow terror attack at a concert hall on March 22 that left 144 dead.
Police in Madrid and Paris have stepped up security ahead of the matches.
Meanwhile, the Met Police said today they have a "robust policing plan" for at the Emirates this evening but the "substantial" threat level remains unchanged.
Chris Phillips, a security expert and former police officer, told The Sun that the security op will even stretch beyond stadiums to city centres and busy transport hubs.
After ISIS singled out the game locations, he said armed cops will be on the lookout for trouble at “train stations, bus stations, even airports" which he says will be "an easier target”.
He said at-risk areas in London, Paris and Madrid will likely be crawling with "firearms officers" with sniffer bomb dogs to deter any terrorist threat.
They're also likely to be stationed on roofs to observe any threats developing on the ground.
Spain is set to deploy 2,000 extra police officers to guard the Real Madrid versus Man City tonight despite maintaining its terror alert remained at four out of five.
France’s interior minister, Gérald Darmanin, warned the security around Wednesday’s match between Paris Saint-Germain and Barcelona was being “considerably reinforced”.
He added: “We have seen, among other things, a communication from Islamic State that specifically targets the stadiums."
In France, Phillips says they could wheel out "soldiers as their backup in the city centres", ahead of the Paris Saint-Germain versus Barcelona match.
The country has already increased its security alert rating to the highest level following the Moscow terror attacks.
At the Emirates
Arsenal's Emirates Stadium will host the first leg of the Gunners' last-eight tie against Bayern Munich tonight.
Despite ISIS's sick threat, Arsenal released a statement saying tonight's fixture will be "no different" from normal.
Security specialist Will Geddes said the almost 70,000-seat stadium will be ready to face any threats - but would likely be gearing up for a major "multi-layered" security operation.
He told The Sun that Arsenal will be working "hand-in-hand with British counter-terrorism police and our security services".
"Tonight all the lessons learned from the Manchester Arena bombing will be on display," Geddes added.
"There will be a multi-layered plan - standard contract security, all the blue light services - police, fire brigade and ambulances - suspicious behaviour and detection teams, canine teams searching for devices, spotters including plainclothes and uniform officers."
The security expert predicted that spotters were also likely to be stationed on roofs and the counter-terrorism specialist firearms officers could have been drafted in along with UK special forces.
Geddes, who has previously worked with a number of Premier League clubs on their security, said they are "switched on" and are likely to have it "all sewn up".
Like Phillips, he said there is a risk to local neighbourhoods and other areas in London which ISIS may have designated a "secondary target" - "anywhere that would garnish sufficient publicity".
The UK is not yet at the terrorism threat level or France or Spain, but Geddes said: "Even though we haven’t yet raised the threat level, it won’t be that long until we do."
THREAT LEVEL
Deputy Assistant Commissioner Ade Adelekan, who oversees the policing of London, said the terrorism threat remains at "substantial" ahead of the match.
Adelekan added: "As ever, we ask the public to remain vigilant, and if they see anything that doesn't look or feel right, then report it to police or security staff."
"All matches are planned to go ahead as scheduled with appropriate security arrangements in place."
Security expert Phillips warned that the UK must not ignore the threat or a resurgent ISIS.
He said: “There is a rise in ISIS. There's no doubt about that.
“We've got people in the UK that are ready and willing to act and across Europe, so this is a problem. It's not gonna go away.
“And I think we will be seeing terrorist attacks over the coming months."
European football's governing body UEFA has also issued a statement addressing the terror threat.
"UEFA is aware of alleged terrorist threats made towards this week's UEFA Champions League matches and is closely liaising with the authorities at the respective venues," the statement said.
