"Investments", noted the US ambassador in Rome last month, "are not made where they are not welcome".
George Bush's envoy, Ronald Spogli, was not just stating the obvious. His observation was part of a wholly undiplomatic attack on his host nation, sent as an open letter to Italy's bestselling daily, Corriere della Sera.
Mr Spogli decided to vent his feelings after prime minister Romano Prodi's centre-left government had scotched a bid, spearheaded by the US telecoms company AT&T, for the company that controls Telecom Italia. His initiative underscored the fact that Italy's treatment of foreign investment is fast becoming a source of international tension. Independently, the European commission is investigating the Prodi government on suspicion of meddling in mergers and acquisitions.
It may not need to look far for evidence. Mr Prodi's government, like its predecessors, makes no pretence of seeing it as part of its role to shape corporate Italy. It doubtless had a decisive say in the big weekend merger between Capitalia and UniCredit.
Telecom Italia was eventually delivered to a consortium led by the Spanish operator Telefónica - but apparently as a result of the kind of political trade-off that is anathema to US and British investors, and indeed the commission. Telefónica joined forces with a string of Italian investors to ensure that Telecom Italia stayed in Italian control after a meeting between Mr Prodi, and his Spanish counterpart, José Luis Rodríguez Zapatero. The same meeting is believed in Italy to have unblocked efforts by a Spanish firm, Abertis, to buy Italy's Autostrade. That move, too, had run into government resistance.
Giacomo Vaciago, professor of economics at the Catholic University in Milan, cannot see what all the fuss is about. Italy's attitude to foreign investors is "typical of most countries", he says.
"It was the same in England in the 1960s and 70s. Only after Mrs Thatcher did you start to play the game of 'Anyone Can Come'".
His outlook - he talks of foreign investors "approaching our coasts" - is dominant in a still young nation that is more nationalistic than outsiders might imagine. For example, newscasters, weather forecasters and newspaper headline writers habitually refer to Italy as "our country" and to the government as "our government". Politicians rarely explain the benefits of inward investment, finding it easier - and more popular - to call for the defence of italianità (italianess)
Nor do they seem much concerned if that is at odds with an avowedly pro-market stance. Pier Luigi Bersani, the minister for economic development, is charged by Mr Prodi with liberalising the economy. Yet his reaction to AT&T's bid was to call it "disturbing". Silvio Berlusconi, the conservative opposition leader, first of all criticised the government's interference in the Telecom Italia affair and then declared his readiness to join other Italian investors in preserving the group's italianità
Professor Giorgio Barba Navaretti, who teaches economics at another Milan university, the Statale, suspects patriotism is, in fact, a red herring.
"As far as the big utilities are concerned, there is probably an idea that Italian investors can be influenced and controlled more than foreign ones. This is not just a question of fulfilling public objectives, in the sense that you want to ensure every small village in Italy gets connected: there are parts of the Italian economy - the big businesses - which are run partly on a system of exchanged favours, between different economic groups and between those economic groups and the government."
Giacomo Vaciago argues that the utilities targeted by foreigners recently fall into an exceptional category. "If you want to buy a company making spectacles, you can easily buy it if you like. The same applies to Ferrari or any other famous Italian name. In fact, in the fashion business, you see the French buying a lot of famous Italian names."
Finding suitable targets is nevertheless difficult because of the nature of corporate Italy. "The family capitalism we have is not easy to enter into," Prof Vaciago acknowledges.
The proportion of publicly quoted firms is low by international standards. And even among companies whose shares are traded, effective control often rests with a family or a shareholder pact.
Informal syndicates whose members vote together on company policy are the defining idiosyncrasy of Italy's capitalism. Although they came into existence as a way of controlling companies on the cheap, one effect of their proliferation has been to deter outsiders. The firms they control account for half the capitalisation of the Milan Borsa.
Once foreign investors have found and bought the right company, they often find that to do business in Italy they need a degree of political goodwill that would be unthinkable in Britain or the US. Potential overseas investors usually discover their Italian rivals have secured that goodwill in abundance.
The need for local contacts cannot be overstressed. As Prof Vaciago puts it: "We don't like foreigners in this country. We welcome friends." But, for foreigners, making friends can create other problems. One is that it can lure them down murky paths in a country that ranked behind Jordan and Uruguay in Transparency International's 2006 index of perceived corruption; a country in which, according to the national retailers' association, every 13th entrepreneur gives a share of his or her turnover to organised crime.
The other problem is that Italy has no less than four levels of official decision-making - national, regional, provincial and municipal - none of which is beholden to the other and many of their areas of responsibility overlap. Securing the support of, say, a rightwing town council that authorises building permits can mean alienating the centre-left regional government that clears projects on environmental grounds.
The gas exploration and production business BG has so far spent €200m (£137m) on trying to build a plant outside the southern city of Brindisi. Italy desperately needs gas for its energy mix and the project was backed by Rome four years ago. But BG has been unable to win over local politicians, and the national government has so far been unable to overrule them.
In February, one current and two former BG managers were arrested on the orders of prosecutors investigating the alleged payment of bribes to speed up the project. A company spokesman said at the time: "We do not tolerate corruption in any form."
The project has been at a standstill ever since.
When in Rome ...
When the coach firm Terravision London started operating in Rome in 2002, its venture could not have been more straightforward. As in several other countries, they had deals with low-cost airlines to ferry passengers from out-of-the-way airports, in this case Ciampino, to the city.
Five years on, Terravision is pressing criminal charges against 20 local police officers, suing a politician for slander and pursuing a case in Brussels against the Italian government. Executives of the company claim they have run into concerted efforts by two Italian bus services, backed by local politicians, to take away their business. "We think an attempt is being made in Rome to shut us down," said one.
Three times since last September, the regional government has approved a rival, publicly subsidised service. Three times, it has been blocked by the courts. But acting on purported irregularities in Terravision's own situation - the local politician being sued described the firm as operating "at the limits of legality" - police earlier this year impounded the firm's coaches.
They have since been returned but travellers arriving at Ciampino may find them hard to find since they have been given parking spaces closer to the departures end of the terminal than to arrivals.
