Paris shootings - analysis: Why is there such a huge military operation surrounding a building with two gunmen in it?

Huge numbers involved would be way of reassuring a French public understandably fearful of start of a jihad

Police vans are lined up in Dammartin-en-Goele, northeast Paris, as part of an operation to seize two heavily armed suspects

The hunt for the two gunmen who carried out the Charlie Hebdo murders has turned into a massive operation with hundreds of security personnel, including special forces, involved along with attack helicopters.

The last time some of us had seen this sort activity by the French military was during the Mali conflict when they were sent to take part in a war against Islamist fighters.

The authorities in Paris say this level of deployment is necessary because Cherif and Said Koachi were hiding on an area, Foret de Retz, which measures 32,000 acres. Since then, however, they have moved to a building, ironically a printworks. What we are witnessing now is a prelude to shootout in which they would be killed, or would surrender.

A French Army helicopter with intervention forces hovers near the scene of a hostage taking at an industrial zone in Dammartin-en-Goele, northeast of Paris

The huge numbers involved would be a way of reassuring the French public understandably fearful of the start of a jihad in the heart of Europe. Questions are already being asked about failures of intelligence around the killings and the policing operation which followed and the size of the operation could be seen partly as a reaction to that.

The Koachi brothers have long been on the radar of the security services who have been able to chart their radicalisation since the Iraq war. Despite that they were able to acquire Kalashnikov semi-automatic rifles and, according to some accounts, rocket-propelled grenades.

Police mobilize with reports of a hostage situation at Port de Vincennes

The government has been saying for weeks that an Islamist attack was very likely. Despite that the Koachi brothers were able to make their way into the offices of Charlie Hebdo, known to be a prospective target in one of the busiest parts of the capital, carry out a massacre, execute a policeman in the street outside, and then make their getaway.

Since then they have managed to drive long distances on main roads in cars which should have been tracked, especially with the presence of helicopters.

Now the siege at the kosher bakery near Paris means further major armed units in the streets. An inquiry will undoubtedly take place about what went so badly wrong when the killings come to an end.