Wars are started for economical reasons as well. If a country gains control over other countries, it benefits their economical interests. As of the times of the Romans, countries have needed expansion of their influence and power to boost their economy. The Romans needed to make wars to get slaves, which were the power house of their economy. Today the U.S.A is expanding its control on other countries through wars. For example if there will be a war against Iraq in the near future, the U.S.A will be able to control petroleum prices, and consequently could control the economical development of many countries.
Countries also tend to want to stay dominant. They oppress weaker countries to stop them from going head to head with them. When India gained independence from the British, they divided the country into two, which they justified as being best for the two large majorities of India. Consequently this helped the conflict grow and the separated countries, Pakistan and India, are degenerating their economies day by day with large military build ups to protect themselves without any stable financial support. The reason behind this division is that a combined India and Pakistan could have been a potential world power, which is not in the interest of European countries. Pakistan and India have had 3 wars since the separation.
Another reason for global unrest is the constant development of military weapons. Although the cold war between Russia and U.S.A has been over, military developments continue. Countries with large military funding constantly develop better weapons to overwhelm the military abilities of potential enemy countries. Minor conflicts due to this between countries can grow into complete wars. Full scale wars can start due to military developments. Although the cold war is dubbed as an arms race between the U.S.A and Russia, it was major cause of many wars such as the Korean War and the Afghanistan war. Military build ups clearly lead to no benefit than to increase the after affect of war.
The main question here is that if the world is filled with dirty politics, worldly interests and hunger for power, could there be world peace? Some people may say that world peace is possible as long as differences between countries are abolished and the world countries focus on economical development without any need for taking arms. I think that this can only be accomplished if the countries accept one political system, if they accept one leader, if they abolish all military development programs, if they abolish economical interests and if they accept one ideology. As you can see when it comes to world peace there are a lot of "ifs". These things are humanly impossible since no country would like to be dominated in any way by another country and is ready to give up its existing power.
As we have seen having a peaceful world today is virtually impossible. Conflicts and wars come and go constantly and mercilessly and it is very disheartening to see that world peace is not possible in near future. Infact it’s a mere myth.