[xzins]

After seeing some blurb on Fox News about some Muslims standing ready to assist the Ukraine, I wondered if it was propaganda. I thought "Maybe they do have a large Muslim population. Maybe I should reconsider who are the good guys and bad guys. But, I was wrong.

After I went to the CIA World factbook.

World factbook information about religion in the Ukraine: https://www.cia.gov/library/publications/the-world-factbook/geos/up.html

Religions:

Ukrainian Orthodox - Kyiv Patriarchate 50.4%,
Ukrainian Orthodox - Moscow Patriarchate 26.1%,
Ukrainian Greek Catholic 8%,
Ukrainian Autocephalous Orthodox 7.2%,
Roman Catholic 2.2%,
Protestant 2.2%,
Jewish 0.6%,
other 3.2% (2006 est.)

[annalex]

In the Ukrainian Census in 2001, 248,200 reported that they are Crimean Tatars.[8] Of these, 243,400 lived in Crimea.[9] In addition, 1,800 Crimean Tatars lived in the city of Sevastopol,[8] which lies on the Crimean peninsula but has a special status.

As of 2012, there are an estimated 500,000 Muslims in Ukraine and about 300,000 of them are Crimean Tatars.[1]

About 150,000 remain in exile in Central Asia, mainly in Uzbekistan. The official number of Crimean Tatars in Turkey is 150,000; some claims are as high as 6,000,000, which would presumably indicate all Turks with at least some Crimean Tatar blood.

Wikipedia 1

And also

According to a 2009 Pew Research Center report, there are an estimated 456,000 Muslims in Ukraine.[15] In the Crimea, the Ukrainian Muslims make up to 12% of the population. A major part of the south steppes of modern Ukraine at a certain period of time belonged to the Turkic peoples, most of whom were Muslims since the fall of the Khazar Khanate.

The Crimean Tatars are the only indigenous Muslim ethnic group in the country.

Wikipedia 2

Population of Ukraine is 45.59 million (2012) so they are about 1 percent. However, they are mostly in Crimea, so percentages their make them a sizable and a single largest minority:

Percentage of Crimean Tatars by region in Crimea
according to 2001 Ukrainian census

Note that the Orthodox (of whichever patriarchate) is, so to say, the default confession; their numbers are probably grossly inflated compared to if you were to take active religious practice into account.

But infiltration of Muslim fighters from the neighboring North Caucasus regions is possible. They are obviously not counted by any census. After the Chechnya wars, they would be happy to volunteer for any anti-Russian cause.

[Cronos]

many are still atheists. There are some Tartar Moslems

But anyway, this is not a case of ethnicity v/s ethnicity --> Ruthenians and Muscowites are ethnically nearly the same. It's more about a way of thought/life -- you can compare the differences to that of the Czechs and Slovaks (not completely, but similar) -- the Ukrainians never developed a centralised mono-culture like their Russian or Polish neighbors.

[Cronos]

I doubt the wider Moslem world would help the Ukrainians against the Russians. The Ukrainians are descendants of Cossacks who were the ones who did much of the "dirty work" against Tartars, Circassians etc.

Also, Ukrainians wouldn't support Tartars against Russians.