There's perhaps no better example of how much the world has changed since the fall of the Berlin Wall 20 years ago and the end of the Cold Ware shortly thereafter, than the following: an American flips a switch to turn on a light in his or her home and the power came from where?

The Soviet Union.

That's right: from the Soviet Union. Unknown to many Americans, about 10% of the electricity in the United States is generated by fuel from dismantled nuclear bombs, including Soviet-era ones, The New York Times reported. Today, 45% of the fuel in American nuclear reactors stems from former Russian bomb material.

Possibly more than ever before, smart stock investing requires a clear and wide forward view. If you don't have an undeniable road map for where your chosen companies are headed, you must dig deeper and you need to do it right now. Specifically, if the companies that you have chosen to invest in don't have a declared international focus, you must be certain of why that is and if it's appropriate.

Barring some unforeseen worldwide economic crash, which is in fact extremely possible, the fact sheet on investing these days is headed with the word global. If your portfolio is not thoroughly salted with companies that do business on a worldwide scale, then your portfolio is scheduled to wither and wane over the next three to five years. Global diversity is essential right now, and will continue to be a requirement from here on out.

It's my opinion that one of the most important criteria these days for successful portfolio building is to create a portfolio footprint that covers at least three different countries. If you have the funds to spread out and you're a fan of diversity, just for safety I suggest that you base your portfolio across five to seven countries. I would suggest the following research focuses as a sample to get your global thinking started.

Consider China for heavy manufacturing, machinery, electronics manufacturing, and a range of consumer goods. I'd be shy of putting any money over there at the moment, however, because to me their stock market is currently overinflated in value.