I'm old enough to remember when the conventional wisdom was that Japan would eventually buy up most of America and that their economic miracle would continue indefinitely.

But then came the shocks of the 1990's which included a bank meltdown and stagnating growth. No one talks of Japan surpassing the US anymore, and for two decades, the Japanese economy has basically been treading water.

Now, in a riverboat gamble of unprecedented proportions, the Japanese central bank is going to set a new standard for massive stimulus; a $1.4 trillion infusion of cash into the Japanese economy that will seek to reignite economic growth and pull the country out of its doldrums.

Reuters:

"This is an unprecedented degree of monetary easing," a smiling Kuroda told a news conference after his first policy meeting at the helm of the central bank.

"We took all available steps we can think of. I'm confident that all necessary measures to achieve 2 percent inflation in two years were taken today," he said.

One of those steps was to abandon interest rates as a target and become the only major central bank to primarily target the monetary base -- the amount of cash it pumps out to the economy. It adopted a similar policy in 2001-2006, but not on this scale.

The scope of the changes Kuroda pushed through, and the fact he secured unanimous board support for them, drove the yen down sharply, knocked the 10-year bond yield to a record low, and nudged Tokyo share prices just shy of a 4-1/2 year closing high.

"The result is nothing short of regime change," HSBC's Japan economist Izumi Devalier said in a report.

"The BOJ has now made a much firmer commitment to achieving its 2 percent inflation goal, and has demonstrated that it will do anything short of foreign-bond buying to achieve this goal."

The scope of Kuroda's overhaul offered immediate comfort to Japanese markets, but contains major risks.

It could leave the central bank heavily exposed to government debt and potentially huge losses if it failed to stoke inflation and investors lost faith in its efforts to revive the economy, and it could trigger a currency war as other Asian exporters seek to remain competitive with a weaker yen.

"It is as if we've gone back to the quantitative easing of the 2000s," said Hiroaki Muto, senior economist at Sumitomo Mitsui Asset Management in Tokyo.

"Targeting the monetary base will lead to a huge increase in current account balances that commercial banks keep at the BOJ, but I'm still not sure if this money will move through the economy."

Not even Ben Bernanke in his wildest dreams could realize this kind of stimulus.

Will it work? "Hard money" analysts appear to be appalled and believe it could lead to catastrophe. "Soft money" experts are far more confident. Previous efforts by the BoJ to stimulate the economy have failed. The question is, was it because the effort wasn't massive enough?

Call it the "Paul Krugman Plan" after the NY Times columnist who keeps saying the US needs a trillion dollars more in stimulus spending to get the economy going again. I guess we're going to see if he's right or not.