The Swiss Guards have been given anti-terrorism training, and now carry SIG P75 pistols and Heckler-Koch MP5 sub-machine guns, as well as their traditional halberds.
Vatican security forces now include an anti-bomb squad and a rapid response team, according to Domenico Giani, the head of the Holy See's 130-man gendarmerie.
The Vatican will also work more closely with Interpol to gather information on any threats, he said.
The deal with Europol, the pan-European police agency, will give the Vatican access to a large data bank of suspects and information on the latest anti-terrorism techniques.