The reason why I asked was because I saw a movie and that question came up in my mind.
Racist doesn't seem to be the right word, as country doesn't necessarily imply race.
An example of how it might be used would be:
This movie was about a group of ______ who victimised immigrants from the neighbouring country.
TL;DR: There's no specific word for people who vilify or are prejudiced against other "countries". The closest general term would be bigot, but there are also terms for prejudice against certain specific nations/nationalities or ethnicities.
It's important to use the correct terms. Firstly, the term you're looking for is not "racist", since this can only be used in relation to race rather than nationality, ethnicity or "country".
Merriam-Webster defines racism as:
1: a belief that race is the primary determinant of human traits and capacities and that racial differences produce an inherent superiority of a particular race
2a: a doctrine or political program based on the assumption of racism and designed to execute its principles
2b: a political or social system founded on racism
3: racial prejudice or discrimination
[Interestingly, racism is a relatively recent term. Merriam-Webster cites its first known use as 1902. That's not to say the concept or the practice didn't exist before then; M-W's dictionary entry includes two full paragraphs on "The History and Dictionary Meaning of Racism", and is worth reading].
So, is there a specific word for people who vilify, or are prejudiced against, other "countries"? The answer is no. In the absence of a specific word, the most applicable general term would be:
a person who is obstinately or intolerantly devoted to his or her own opinions and prejudices
especially: one who regards or treats the members of a group (such as a racial or ethnic group) with hatred and intolerance
[Merriam-Webster]
Bigot significantly pre-dates racist: M-W says the first known use was in 1660.
The term bigot shouldn't be confused with xenophobe, though no doubt there are parallels between the two. Merriam-Webster defines xenophobe as:
one unduly fearful of what is foreign and especially of people of foreign origin
M-W also offers the following broader background and explanation:
Xenophobe is partly based on the Greek noun xenos, meaning "stranger, guest, foreigner". Unlike other phobias, xenophobia isn't really considered an abnormal condition; instead, it's generally thought of as just serious narrow-mindedness, the kind of thinking that goes along with racism and extreme patriotism. In times of war, a government will often actually try to turn all its citizens into xenophobes.
Lastly, there are many words that define a fear, aversion or hatred of a specific nationality, ethnicity or cultural identity. These words are most easily formed with the either the prefix anti- (e.g. anti-American, anti-Semite) or the suffix -phobe (e.g. Anglophobe, Francophobe, Islamophobe). Wikipedia provides a comprehensive list of anti-cultural, anti-national, and anti-ethnic terms.
xenophobic or xenophobia. there are country-specific words, such as anglophobic or francophobic.
While this is more commonly used to refer to preference to / prejudice in favor of a country (typically one's own country), and prejudice against all other nations, nationalist seems to work:
ODO:
A person who strongly identifies with their own nation and vigorously supports its interests, especially to the exclusion or detriment of the interests of other nations.
‘he was a staunch nationalist during his 22 years in power’[adjective]
Nationalist means connected with a person's great love for their nation. It is often associated with the belief that their nation is better than any other nation, and in this case is often used showing disapproval.
Political life has been infected by growing nationalist sentiment.[noun]
A nationalist is someone with nationalist views.
...the small band of nationalists who reject imported American culture and Western-style politics.someone who feels that their nation’s interests should be considered as more important than those of other nations
The right-wing nationalists won 43 seats.a person who strongly believes their country is better than others:
violent protests by nationalists
Most of the above are secondary definitions; primary definitions include:
ODO:
A person who advocates or supports the political independence of a particular nation or people.
‘a Basque nationalist’[adjective]
Nationalist means connected with the desire of a group of people within a country for political independence.
The crisis has set off a wave of nationalist feelings in Quebec.[noun]
A nationalist is someone with nationalist views.
...demands by nationalists for an independent state.someone who believes that their group, state, or nation should be independent
Serb/Kazakh/Zulu nationalistsa person who wants their country to be politically independent
IMO, the word nationalist could be used in the sample sentence in the question, and it would be understood with the desired meaning.
nativist:
Nativism is the political policy of promoting the interests of native inhabitants against those of immigrants,[1] including by supporting immigration-restriction measures.[2] https://en.wikipedia.org/wiki/Nativism_(politics)
