to be at war
The Spanish phrase 'estar en guerra' is translated into English as 'to be at war'. This phrase is often used to depict a state of open and declared armed hostile conflict between states or nations, or a period of such conflict. It can also be used metaphorically to express a condition of rivalry, as in competition or conflict between persons, groups, or concepts.
Our countries should not be at war.
It is a declarative sentence expressing the speaker's viewpoint, stating that there should not be any war between their respective countries.
Please, stop acting as if you were at war with the world.
This is usually used when someone is behaving aggressively or defensively, and is advised to calm down or to adopt another attitude.
Many think that the two companies may be at war in the market very soon.
This is a metaphorical usage referring to a strong competition between two business entities soon in the market.