There are many pretexts to start a war. Most of the time it is a reason to get hold of oil. Other times instead for interests of other raw materials. But it can also happen that the reasons are more (serious) as for example those of nuclear weapons. Iran has been repeatedly warned of nuclear weapons, the construction of which has often been kept in the dark about public opinion.
A few days ago the US killed the Iranian general Soleimani who raised fears of a new conflict that could involve many world countries. any suspected that the drone that killed the general left from the US military base in Sicily, but the Italian defense ministry denied today.
In the modern era, the most technological countries have unimaginable weapons for countries of “modest” size. In the future, nuclear wars are likely to be fought from an IT point of view, attacking the vital servers of the systems and cities to be affected.