1. The four factors were aggressive nationalism, imperialism, power blocks and militarism. 

2. The USA was involved in most of the wars that were fought during the last ten years. 

3. Iraq War: The USA attacked Iraq blaming the regime of Saddam Hussein in 2003. From then till 2011 American forces were there in Iraq. They tried Saddam and executed him. 

4. War in North West Pakistan: Taliban, a militant Islam Group formed for separate nation from Pakistan and fighting with it from 2004. The USA sent troops to quell the agitation. But it Is not decimated yet. 

5. Somalia War (2006 – 2009): There were ethnic differences led to large scale fighting In Eastern Africa in countries like Somalia, Ethiopia and Eritria, etc. 

6. An Islamic militant outfit Al-Queida (under Osama Bin Laden once) intruded Into Yemen in 2010. 

7. In 2007 there occurred Transahara War in Northern African countries Morocco, Tunisia and Mauritania, etc. 

8. Most of these wars are of militant nature.