The only time they're unislamic is when your nationalistic desires are in conflict with the core teachings of Islam.
"He is not one us who calls for `Asabiyyah, (nationalism/tribalism) or who fights for `Asabiyyah or who dies for `Asabiyyah."
And in another Hadith, the Messenger of Allah (saaw) referring to nationalism, racism, and patriotism said:
"Leave it, it is rotten." [Muslim and Bukhari] and in the Hadith recorded in Mishkat al-Masabith, the Messenger of Allah (saaw) said,
"He who calls for `Asabiyyah is as if he bit his father's genitals."
Also, the Messenger of Allah (saaw) said, narrated by At-Tirmidhi and Abu Dawud,
"There are indeed people who boast of their dead ancestors; but in the sight of Allah they are more contemptible than the black beetle that rolls a piece of dung with its nose. Behold, Allah has removed from you the arrogance of the Time of Jahiliyyah (Ignorance) with its boast of ancestral glories. Man is but an Allah-fearing believer or an unfortunate sinner. All people are the children of Adam, and Adam was created out of dust."
Also, the Messenger of Allah (saaw) said,
"Undoubtedly Allah has removed from you the pride of arrogance of the age of Jahilliyah (ignorance) and the glorification of ancestors. Now people are of two kinds. Either believers who are aware or transgressors who do wrong. You are all the children of Adam and Adam was made of clay. People should give up their pride in nations because that is a coal from the coals of Hell-fire. If they do not give this up Allah (swt) will consider them lower than the lowly worm which pushes itself through Khara (dung)." [Abu Dawud and Tirmidhi]
http://www.zawaj.com/editorials/nationalism_ahmed.html