With virtually every stock market rally comes talk that American investors finally are shaking off fears over European debt contagion. So it shouldn’t surprise that the 2012 stock surge is no exception.

The story goes that the market is “decoupling,” – that is, shaking off euro-land panic and instead focusing on the nascent U.S. economic recovery. In this scenario, stocks and the dollar can glide higher together while American investors remain blissfully unaware of the debt storm abroad.

Just don’t try selling it to Bob Janjuah, the flame-throwing co-head of global macro research at Nomura Securities, who believes decoupling is a myth that will be exposed sooner rather than later.

“Yet again, and certainly for the third year in a row, we are being told that the U.S. is over the worst and that a sustainable recovery is here,” Janjuah told clients. “We are expected to believe another ‘decoupling’ fairytale, only this time around neither Asia/EM (emerging markets) nor the Eurozone really matter to the U.S. economy.”

Inaction by leaders both in Europe and the U.S. to attack dual debt crises will hit investors later in the year, he said. In particular, he attacks the “neo-communist experiment in the West that relies on more debt and printing money in order to maintain the status quo.”

More specifically, Janjuah said a full default – rather than the partial, ostensibly voluntary investor haircuts that have taken place so far – will lay waste to the notion that Europe’s problems can be isolated.

Not even more quantitative easing measures from the U.S. Federal Reserve or European Central Bank will be able to prevent the ensuing economic collapse, according to the forecast.

“The worst of the Eurozone mess is still ahead of us,” Janjuah said. “This is in spite of the attempts by the ECB and national Eurozone central banks to rule out QE with one hand, yet at the same time engaging in the worst form of policy behavior and de facto QE with the other and with a hard Greece default likely this quarter.”

Janjuah is swimming upstream in the decoupling argument, so long as equity markets are rallying.

Benjamin Bowler, global equity derivatives strategist at Bank of America Merrill Lynch, said implied volatility in the Standard & Poor’s 500 is in sharp decline, “suggesting that US markets appear to be decoupling from the travails of Europe.”

But Janjuah is sticking to his forecast – that global growth will hit the skids and the S&P 500 is on its way to 800 this year.

“One day, when we collectively abandon the neo-communist experiment in the West that relies on more debt and printing money in order to maintain the status quo, then I will hopefully have a different and far more positive view of the years ahead,” he said. “I look forward to this time. But for now, expect more of the same as in 2011.”

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