Shawn DonnanWorld trade editor at the Financial Times

The answer ought to be an easy “yes.” But it isn’t. Defending strategic industries and assets starts with defining them. And that’s a conversation that all too often ends up taking countries down a protectionist path.

There are, of course, the easy and obvious strategic assets. Power plants and grids, ports, and roads all deserve the label. You can probably include a country’s digital infrastructure and maybe even some of its food supply chain.

But the conversation quickly gets murky beyond that.

In a knowledge-based economy, human capital is an increasingly important asset. But is a German research scientist a strategic asset worth defending from a Chinese company’s lucrative job offer? Is a French tech pioneer worth protecting from a Google recruitment drive?

Consider Canada’s “strategic” maple syrup reserve. What ought to be a joke in a bad film, isn’t. Instead it is an all-too-real economic tool worthy of Beijing’s finest state planning minds that for decades has helped fix prices and control supply and, inevitably, had an impact on farmers and consumers across the border in the U.S. state of Vermont.

If a Chinese state-backed food giant were to start buying up maple farms in Quebec, would that be an assault on Canada’s strategic infrastructure?

Put that in a European context. Would a Chinese bid for a Parma ham producer come under the same scrutiny? A New Zealand dairy giant buying up French butter producers? A U.S. agribusiness’ purchase of Danish pork farms?

There’s nothing wrong with protecting strategic assets. But let’s be careful how we define them.

Philippe Le CorreNonresident senior fellow in the Europe and Asia Programs at the Carnegie Endowment for International Peace

The answer is an emphatic yes. In today’s business world where cyber and competition issues are critical, it is essential for EU companies to protect themselves. In a number of European countries, China has invested into strategic sectors such as energy, utilities, port, and airport infrastructures. For example, China Three Gorges, a state-owned enterprise, controls 23.27 percent of Portugal’s national grid company, EDP-Energias de Portugal (it recently raised its stake from 21.35 percent, with few people even noticing), while COSCO—China’s largest shipping company—now runs Piraeus, Greece’s main harbor.

China has also been actively pursuing European technology companies through mergers and acquisitions, which has led to a debate in Germany about robotics or semi-conductors—two of the most cutting edge sectors in the German industry. Will Germany remain the leader of these fields, or will it be supplanted by the United States or China? The Federation of German Industries (BDI) thinks there’s nothing to be worried about as German technology still performs well, for example in robotics. Yet, analysts are less sure. In his State of the Union address last month, European Commission President Jean-Claude Juncker insisted that EU member states should share with the Commission details of a proposed acquisition on grounds of security or public order. This includes major programs in the areas of research, transport, energy, and space (Galileo).

Stefan MairMember of the executive board for the Federation of German Industries (BDI)

Any form of investment control ultimately affects the functioning of a market economy. The right of entrepreneurs and shareholders to sell companies is a core element in the exercise of private property rights. Any measure that affects this right can only be justified for the sake of protecting another higher public good. This is certainly the case for security and public order, but is it when it comes to the protection of strategic sectors and key technologies? And if so, is investment control the right means?

Are key technologies and strategic sectors more threatened by the takeover of a midsized company by a Chinese investor, or by the transfer of research and development departments and data storage capacities of multinational companies to China? And who defines what a strategic sector is? Not long ago, the steel sector was certainly classed as one and data processing was not. Can governments know what will become the key technologies of the future? In the 1980s, almost nobody would have expected mobiles phones to become one.

There are serious fundamental and operational questions involved in broadening investment control—questions that have hardly been discussed yet. They have been overshadowed by a mere defensive approach and hasty proposals to find quick fixes for a long-term strategic challenge.

Jonas Parello-PlesnerSenior policy fellow at the Hudson Institute

Europe should scrutinize foreign investment based on national security. Afterward, it gets harder—as demonstrated by the enormous effort put into disentangling the EU from the Russian gas monopoly. There are considerations of dependency particularly with foreign, state-owned companies in strategic sectors.

Huawei, the nominally private Chinese company, is a case in point. The Americans may have been too paranoid, mostly blocking the company’s proposed deals in the United States. On the other hand, the European countries may have been too naïve, letting Huawei roll into sensitive grids all over the continent without a background check.

Screening investments doesn’t entail that the EU suddenly turns protectionist, as some would allege. The EU is a latecomer to this. The Committee on Foreign Investment in the United States (CFIUS) process is standard procedure in the United States. China also has a national security screening system, although opaque in its limits.

The EU should establish a clear, limited, and rule-bound screening. Introducing such a screening shouldn’t lead to classifying yoghurt as a strategic asset—as tried by French lawmakers when foreign bidders eyed the French dairy giant, Danone. Even with investment screening in place, the EU would remain a top destination for FDI, which is on the uptick after a slowdown in 2014.

Marc PieriniVisiting scholar at Carnegie Europe

Europe should promote its strategic sectors, rather than protecting them. From shipbuilding to high-speed trains, from electric cars to one of the two world leading aerospace industries, European industries have been spearheading innovation in many fields and continue to do so on a daily basis.

They are now faced with new competitors, for example, China in aerospace, railways, and shipbuilding; India in space exploration and biotechnologies; Brazil, Canada, and Russia in small-size aircraft manufacturing.

This new competitive environment has already triggered healthy decisions: the German-French decision to merge their high-speed train manufacturers Siemens and Alstom; a similar decision between France and Italy on shipbuilding; the multi-country European plane maker Airbus setting up production plants in China and the United States.

Europe is also faced with new threats, for example, a protectionist position of principle from the U.S. president and protectionist decisions by China; and an aggressive investment posture by, again, China in strategic European industries.

Forbidding foreign entities from investing in certain European industrial sectors will probably prove difficult in the long term. There is instead an array of alternative measures. This includes protecting European patents; teaming up previously competing EU industries (as in the Siemens-Alstom merger); and jointly promoting their products as well as manufacturing them locally in highly competitive markets.

Gianni RiottaMember of the Council on Foreign Relations

Chinese President Xi Jinping’s speech at the 19th Party Congress lasted for almost four hours, but made very clear that China has a solid geopolitical strategy for the twenty-first-century: investing in Asia and Africa; confronting America on trade and defense; buying off Russia as a vassal; trading with Europe; neatly parting the entire world.

The United States bets on the impromptu tactics that President Trump dictates via Twitter, Russia chugs on under Putin’s steely hand, but divining Europe is difficult task. Brexit; the waves of populism crushing from the Atlantic to Prague; and the referenda in Scotland, Catalonia, Lombardy, and Veneto are a testament to a public opinion that is wary of global powers, and nostalgic of national, homey cultures.

The EU badly needs a common strategic industrial policy (think of the difficult Fincantieri-Stx deal that was painfully negotiated in Rome and Paris by Italian Prime Minister Paolo Gentiloni and French President Emmanuel Macron!) The union does not even have a military, or European industrial arm powerful enough to face the United States, or even China.

Brussels keeps fining the digital giants—like a paunchy policeman jealously slapping a ticket on a brand new, red Ferrari—but does not invest in AI, data, or social media. How can you “protect a strategic sector” if it is not clear that you own one after all?

Marietje SchaakeMember of the European Parliament

Yes, but only when there are legitimate reasons, not as thinly veiled protectionism. The EU is—and should remain—an attractive destination for foreign investments. But openness should not make us naïve. Key enabling technology companies are often strategic, therefore we must assess an investor’s motives and sources of resources. Member states have the freedom to reject FDI for national security reasons already, and EU-wide harmonizing criteria makes sense for the single market.

The EU should continue to pursue its efforts at bilateral and multilateral levels to ensure that third countries offer a level of openness toward foreign investments equivalent to that of the EU. We are open for business, but not at every cost.

Paul TaylorContributing editor at POLITICO Europe

It’s legitimate for Europe to protect truly strategic sectors and technologies against hostile takeovers by state-controlled or opaque investors. The United States, Russia, and China don’t hesitate to preserve national control of strategic industries and to veto unwelcome foreign acquisitions. So why not Europe?

Several EU countries, including Germany, already have review procedures. To ensure a level playing field and avoid abuses, it makes sense for the European Commission to exercise these powers in the single market—except in strictly national industries, such as defense.

The hard part is defining which sectors and companies are strategic, and from whom they should be protected. A French decree lists 30 sectors, including water, energy, transport, health, IT, gambling, and telecommunications, requiring approval for takeovers. Some seem abusive or too broadly drawn. A Gaullist government issued the sweeping decree after rumors that U.S. beverage giant Pepsico wanted to buy French yoghurt-maker Danone.

The EU must understand that countries blocked will likely retaliate against European investments. The example of COSCO’s acquisition of Athens’ Piraeus port shows how EU objectives can clash. By forcing bailed-out Greece to privatize state assets, it has handed China a strategic foothold in Europe’s southeastern gateway.