Twitter users in Italy are unfazed about the ISIS threat to invade Rome, in the wake of the group's brutal beheading of 21 Coptic Christians.

Instead of feeling terror, netizens have responded by ridiculing the Islamic State militants.

Under the #We_Are_Coming_O_Rome, tweets of photos of the city's notorious traffic situation were accompanied by taunts and jokes about how ISIS will enter the city.

Twitter user smarteyes said: "if you manage make sure to come between 1 and 5 AM otherwise no way you getting through!"

User Alessadro Cocco was similarly sarcastic, wishing the group luck in getting to the city with the upcoming transport strike.

Miguel Espes, on the other hand, applauded his countrymen's response to the threat, saying "The answers to #We_Are_Coming_O_Rome are simply glorious. Bravo, Italian people."

Regular citizens, meanwhile, have remained cautious but not overly fearful of the threat.

"I was a child during World War II and have seen good and bad times since then," 77-year old Italo Fienelli, a tobacco shop owner said in an interview with USAToday. "I have learned it is important not to overreact to either extreme."

His sentiment was echoed by 29-year-old tour guide Alessandro Tivoli, who said people cannot live their whole life in fear.

As Italians played down the threat, the government is not taking ISIS lightly and has intensified security in key areas around Rome and the Vatican.

The government is keeping close tabs on the entry of possible terrorists with the constant tide of refugees from North Africa who enter their ports as well as other areas that may prove to be a target by the ISIS members.

The same measures are being undertaken to protect the Vatican. During last Sunday's Mass at the St Peter's Basilica, there was increased police visibility to secure the location but visitors to the Pope's audience did not seem to mind.

"It's a dangerous world, and the Pope and the Vatican have a very high profile," Karen Phifer, an American teacher spending her sabbatical in Italy, said. "Every step that can be taken to protect them should be taken."