2. Border disputes.

3. Religious conflicts.

4. Competing for resources.

In class society, war is the highest form of struggle to solve the contradictions among nations, countries, classes and political groups, and it is the continuation of politics through violent means. There have been many types of wars in human society.

According to the nature of war, it can be divided into just war and unjust war; According to social forms, it can be divided into wars in the late primitive society, wars in slave society, wars in feudal society and capitalist society. According to the form of war, it can be divided into cold weapon war, hot weapon war, mechanized war and information war.

Extended data

War has a direct and important impact on the safety of mankind, the rise and fall of the nation, the survival of the country and the progress and retrogression of society. War will persist and exist for a long time in human society, and will continue to exist and play an important role in the historical development of human society. The demise of war is conditional and it will go through a long and gradual process.

Only with the high development of productive forces and the great progress of society, with the demise of private ownership and class, and with the disappearance of fundamental interest conflicts between countries or political groups, war will eventually lose its soil and conditions for existence and withdraw from the stage of human history.