Switzerland has been called many things. Hedgehog, an epithet popular during the second world war, seems particularly apt now. Then, when it was surrounded by the Axis Powers, it drew up plans to dynamite bridges and tunnels to defend itself from invasion. Now, as the US Internal Revenue Service seeks to force UBS to disclose the names of 52,000 of its US clients, Switzerland has shown its spines again. Bern says it might confiscate the data to prevent Switzerland's largest private bank from releasing them to a Miami court. Alan Gold, its aptly named US judge, has meanwhile asked the US authorities whether they would seize UBS's US assets if the bank does not comply. Diplomats are now stepping in where lawyers fear to tread.

Clearly Bern is not fighting just to uphold UBS's reputation. Neither it, nor UBS, disputes that the bank brought the mess on itself. In February, in a separate but related criminal case, UBS agreed to pay a $780m fine and hand over 250 client names to US authorities after it admitted helping them to evade tax. Rather, Bern wants to uphold its right to apply Swiss law in its own country and halt the advance of US legislative creep. It also seems to want to limit the damage that could be wreaked on Switzerland's private banking industry by a showcase trial in Miami, America's own offshore wealth management metropolis. Doris Leuthard, Swiss economy minister, has called for a settlement.

In riding roughshod over Switzerland in its pursuit of errant American taxpayers, the US approach is at odds with President Barack Obama's more conciliatory style, extended even to former foes. Such actions also sit uneasily with the two countries' recent tax treaty. Washington seems intent on blowing up rather than building bridges to an inoffensive, if prickly, country.