Is there a place in modern society for strong nationalistic feelings, and how do they affect international relations?

Strong nationalism, when given too much power, severely impacts foreign relations in a negative way, as some strong nationalists promote their interests for their own country, even if it impacts others. However, nationalism to a certain degree is not necessarily harmful, and citizens should be allowed to support and advocate for their country. It only becomes an issue when it is a detriment to other countries.