Something important happened last Friday in Brussels, although you’d never guess from the media coverage here (The Washington Post relegated coverage of the EU summit to page 19 yesterday).

British Prime Minister David Cameron’s decision to walk away from a budget tightening deal with the other 26 members of the European Union aimed at saving the euro has caused upheaval within the ruling U.K. coalition, roiled relations between Britain and the rest of the EU and put the issue of Britain’s future membership of the EU back on the table.

Britain has always had a groundswell of Euroskepticism but that is no longer confined to the outer rim of Cameron’s Conservative Party and the Tory press. Two polls since Friday — published in Euroskeptic papers the Mail on Sunday and The Times — showed strong backing for Cameron’s stance in Brussels, a majority for a referendum on EU membership, and support for pulling out of the EU altogether. But also a poll in The Independent published before the summit found that 52 percent of Britons see the euro crisis as an ideal opportunity for Britain to leave the EU.

Cameron’s Liberal Democrat partners in the coalition are dismayed, saying that his “veto” — a misnomer because he never blocked anything as the eurozone countries plus others decided to go ahead anyway — would isolate and marginalize Britain.

So let the battle commence! The fact is that Britain has not had a serious conversation about EU membership since 1975, when a referendum produced a yes vote for staying in the EEC. Cameron is justifying his stand in Parliament today.

Others have already starting looking at the alternative to EU membership and are not convinced. The Economist, for example, suggested that Britain would look like “Switzerland with nuclear weapons” — in a best case scenario. If that were the outcome, Britain’s usefulness to the United States would be severely diminished.

This conversation matters — particularly to the U.S. If the cold wind of recession blows from Europe across the Atlantic in a U.S. election year, there will be consequences for American jobs. The United States should understand that Britain is more useful as a member of the EU club than as an island nation floating off the northwestern tip of Europe.