“The fact that they summoned the Russian ambassador here in Rome is also an important step towards a tough direction vis a vis Russia.
“But at the same time if we read between the lines we can see that they are still speaking, Rome and Moscow are both talking about a constructive relationship.
“The two countries still have a constructive relationship based on important trade and business issues.”
The Italian Foreign Ministry said a meeting had been held with the Russian Ambassador Sergey Razov to protest the “grave incident.”
Meanwhile, the country’s Foreign Minister Mr Di Maio told a gathering of the Italian Parliament that the espionage operation was a “hostile act of extreme gravity.”
A statement issued by the Carabinieri described how the Italian Navy officer had been caught “red-handed”
It read: “During a clandestine operation between the two, surprising them red-handed immediately after the handing over of classified documents by the Italian official in exchange for a sum of money.”
The Russian Embassy in Rome has publically acknowledged the detention of a member of its military attache’s office but would not provide any further comment regarding the incident.
“In any case, we hope that it wouldn’t affect bilateral ties,” said an embassy statement.
Vladimir Putin’s spokesman, Dmitry Peskov, said the Kremlin was unaware of details of the incident.
Mr Peskov noted that “we hope that the quite positive and constructive character of the Russian-Italian relations will be preserved.”
Meanwhile, the Russian Foreign Ministry voiced regret about the diplomats’ expulsion in another statement carried by Russian news outlets.
The Russian Ministry added that its “possible steps in connection with the situation that doesn’t conform with the level of bilateral ties will be announced later.”
British Foreign Secretary Dominic Raab has expressed the UK Government backing support for Italy in a tweet.
Mr Raab said: “The UK stands in solidarity with Italy and its actions today, exposing and taking action against Russia’s malign and destabilizing activity that is designed to undermine our @NATO ally,” he said in response to a tweet from Mr Di Maio announcing the expulsions.