Yes, Nationalism still plays a role in today’s politics in the world.
Nationalism makes a country place his interests above others trying to keep his sovereignty.
United States of America is an example of a country affected by nationalism.
We can see the effects of U.S. nationalism in his polices of not coping with global measures for climate change and protection of the environment, in the way immigration matters are addressed, or on his military intervention actions in others countries.
Others countries that can be named too as affected by nationalism is North Korea and South Korea or Japan.