Concept Of A “Country”

What does it mean when we say that a “country” has done or achieved something? Let’s look at a couple of examples:

• “Country X successfully launched a major space probe.”
• “An underdog team from country X wins a major sport competition.”
• “Country X attacks country Y.”

What or whom exactly are we referring to by “country”? Whom should we congratulate on the achievement? Whom can we blame for the war?