It turns out that it also happens. As an ally of Russia, Montenegro voila the Russian-Japanese war declared war on Japan in 1904.
No territorial claims against Japan at the small Balkan principality of Montenegro, of course, never happened. Montenegrin Prince Nikolai Petrovich Njegos, declaring war on Japan, based solely on historical and diplomatic considerations. Montenegrins have always valued the friendly relations and the protection of Russia, Orthodox state. Saying "together with the Russian us 150 million, and without Russian - two vans", born at the height of the Russian-Turkish war, There is now among Montenegrins.
Participated in the war Montenegrins not symbolically. Of the arrivals from the Balkans and in the service in Russia a few hundred Montenegrins was created and sent to the Far East Volunteer Regiment ("couple"), however, upon arrival at the front of Montenegrins were divided into different parts. Montenegrins fought selflessly. Newspapers of the time wrote a lot about Montenegrin "grandfather", the famous fighter regiment of General Mishchenko ... Then, at the conclusion of peace between Russia and Japan on the small proud country somehow forgotten. It happens. And then did not become a sovereign and Montenegro.
Only in 2006 was it eliminated an unfortunate misunderstanding and was signed that without a peace treaty.
That is, the country formally at war hundred and two years. As they say, nothing personal. Purely politics.