A fresh wave of cross-border merger and acquisition activity is breaking across the Atlantic – and the reactions from Europe's governments to U.S. companies trying to buy their crown jewels have varied wildly.
In the past week, the French government has waded into the fight for control of engineering giant Alstom,which has kicked off between U.S. conglomerate General Electric and German rival Siemens.
Read More French warn GE as Siemens plans Alstom hijack
Across the Channel, Pfizer's interest in AstraZeneca looks set to turn hostile after the U.K. pharmaceutical company declined to engage with an approach.
Both companies are important to their home countries as employers -- and as symbols of the strength of home-grown research and development.
Yet their governments have vastly differing approaches to the prospect of acquisitive foreign predators.
Read More Pfizer's AstraZeneca offer may reach $93 per share
France has summoned Jeff Immelt, chief executive of GE, to a summit with French President Francois Hollande and Arnaud Montebourg, his economy minister. Montebourg has already expressed concerns about the bid.
In the U.K., the government has been silent so far on a potential Pfizer/AstraZeneca deal. The opposition Labour Party has already waded in, with shadow business secretary Chuka Umunna warning of possible "asset-stripping" by Pfizer and potentially negative consequences for British science investment. But, given the old Labour government introduced a tax break on intellectual property tax -- which is one of the reason Pfizer is attracted to AstraZeneca -- they are unlikely to raise too much of a stink.
The protectionism demonstrated by the French government is not the best policy for its business, Sheila Page, senior researcher at the Overseas Development Institute, told CNBC.
"Mergers have a way of failing, but that's the companies' lookout," she said. "There are economic rationale for protectionism, but it's very hard to identify them in practice,unless you are a small developing country with very few big companies."
And protectionist governments may need to brace themselves. The trend of cross-border deals isonly going to get bigger, according to Scott Moeller, Director of the M&A Research Centre at Cass Business School.
"Companies have a lot of cash on their balance sheets, and that's cash they don't have to necessarily use for working capital. They need to put it to work," he told CNBC.
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