Nationalism is frequently misunderstood and maligned as an ideology of a superiority of one nation at the expense of other nations.
Particularly if the nation is associated with ethnicity, it is pooh-poohed for that single reason.
Yet the Nationalism proper is an enforced (via institutions of education, religion, elections etc) unity of the national elite with the national "simple folks", and preferential treatment of the local population, as opposed to the Internationalism: unity of international elites between themselves at the expense of the local simple folks.
The local elite within Internationalism paradigm would rather provide international aid than invest in the local community. Major reason? Within Internationalism, it is simply unsafe to invest locally, as the local uppity people may rebel and dislodge the Internationalist from his sinecure. The money and care should always be coming from some immeasurable distance, like from the God himself. So that there is no opportunity to try and take control of these supplies.
Local communities are but a source of extractable wealth, the feeding and play grounds. One may not invest locally, but one may spend wantonly all the wealth on trinkets and public shows, providing the wealth gives no return whatsoever while instantiating a temporary pleasure. Deliberate destruction of local commons and creation of international, remote commons is what Internationalism offers to our elite as an act of self-preservation.
It is necessary to point out that elites are always inclined toward internationalism. Monarchies of Europe were perfectly internationalist from medieval era onward, especially when it came to marriages; they would only marry across the nations and establish international family cartels. The courtesans were frequently local, although the most successful courtesans were trotting the globe well before the airlines took off. International conferences between the monarchs of Europe were established centuries before the United Nations, and were far more efficient instruments of control and manipulation.
Growing internationalism is always most noticeable in the dominant and prosperous nation ruling elite. French ruling elite of the 18th century run amok with its internationalist aspirations and was soon replaced with its direct opposition - the party of nationalists so rabid that they wanted to rule the whole world in the name of France and its people. So the Chauvinism was born in France out of Bonapartism.
The post-soviet USSR, which has shed worn-out communist ideology, demonstrates this same naked truth about Internationalism: the Russian financial, political and cultural elite is perfectly united with the multicultural and diverse elites around the globe, while acting as an invading army upon enemy territory when dealing with the rest of the local population.
Rampant corruption, complete disregard for national institutions are but the symptoms of this naked Internationalism.
While practicing naked Internationalism, Russian elite propagandizes the thoroughly falsified version of Nationalism to the simpletons. TV audience is to shut up and believe in the Russian exceptional national qualities and in a myth of unbeatable, indivisible Russia under the guidance of its most superb leaders.
Nationalism proper is not about superiority of your own nation. It is more like fucking your own wife. Not because you are superbly proud of her and want to demonstrate her superiority to the rest of the world. You fuck you wife and have children with her not because she is objectively superior to all other women on Earth, but because you love her in the most narrow and concrete biological and social sense. You like how she tastes, looks, acts and you want children with her, to give them your name and your wealth. You invest in your own family and continuation of your and her genes. Indeed, by acting this way you set your own limits, your own borders as you have grown to understand them.
Internationalism is like promiscuity. It is potentially limitless within the given Universe. Imagine there is no country, there is no religion too. There is no Heaven as there are no ancestors who look down upon you. No children are wanted either, and those born by chance are proletarians. You squander your wealth on prostitutes, sophisticated courtesans and exotic dancers. It is fun, peerless, unrestricted and uncontrollable. No borders are needed nor wanted by your boundless ego.
Nationalism requires wise self-restraint on the perfectly natural impulse to fuck the whole world of somewhat better partners.