The major threats can be divided into three categories which can be grouped as exploitation, disruption and destruction of the ICT infrastructure.
Exploitation can be motivated by economic or political espionage, identity theft for financial gain or stealing of customer personal information. A typical example of exploitation is the 2009 GhostNet incident where various governmental bodies were hacked with the help of a Botnet as identified by IWM (Information Warfare Monitor) of Canada. Disruption can be motivated by revenge, competitive advantage or financial gain. The most common disruptive methods are DDOS (Distributed Denial of Service). Botnets are also behind destructive attacks where incidents like Conficker and Marpisa has infected about 7 million machines and over 12 million machines respectively. Destructive can be motivated by warfare where instead of physical weaponry, an attack is based on cyber-warfare. The 2007 Russian Cyber-attack on Estonia can be regarded as a typical case. Although, this is not so common yet, it may happen to electricity smart grids and water systems in terrorist or military acts.
As you can see the above mentioned threats may affect more than one nation or continent and may have a global impact. This is mainly due to the nature of the Internet infrastructure where we have overlapping boundaries.