The Internet is the most important network world-wide. Therefore, it is the most important target for all kind of attacks. The method of choice for protection of sensible data transmitted over public parts of the Internet is cryptography. So-called strong cryptography enables everybody to protect data in a way that nobody without access to the key is able to read the message.
For that reason, many countries restrict the access to this technology. In countries like France cryptography is prohibited in general, countries like the U.S. allow domestic companies and individuals to use strong cryptography but doesn't allow the export. Other countries have been quite liberal up to now, like Germany and other European countries, for example.
Unfortunately, even in these more liberal countries, the views are changing. The Wassenaar treaty is the first try to unify the North American and European countries on the use of cryptography. Because of space constrains, I won't go into detail. For more information, see .
Another approach to control cryptography to remain able to tap world-wide communication is the American "clipper chip", which allows the government to decrypt encrypted documents easily (, see ).
To make it even easier to intercept all public communication, there are many efforts to make network operators change the infrastructure. A newspaper article  reports that governments on both sides of the Atlantic seek to redesign the infrastructure of the Internet to make instant access net tapping a legal requirement. The U.S. passed the Communications Assistance to Law Enforcement Act and in Europe, a document called Enfopol 98 proposes similar actions. Section 4.2.1 covers this in more detail.