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.
Pretty picture.
From the moment of its independence, Ukraine executes practically difficult work on repatriation of the Crimean people and on its social integration in the Ukrainian society.
Kyiv Post
From the larger version of the article:
Ukrainian government is interested in engagement of the international community to the resolution of a problem related to the integration of the Crimean population and hopes both advisory and financial help. So, Ukrainian leadership has intiated negotiations with the government of Turkey as to the possibility on building of three large industrial zones on Crimean peninsula. At the same time, Crimean leaders try to express their unreasonable discontent with a progress in implementation of government programs and state funds allocated to help the repatriated population. Thus they don’t try to take into account Ukrainian and international economic realities. Moreover, recently leaders of Crimean médjlis have tried desperately to internationalize a problem of the Crimean tatars attracting attention of the international community to it, and also involving the European and international organizations. In the middle of September Kiev witnessed the next meeting of médjlis leadership with representatives of diplomatic missions and the international organisations. So, in August, 2010 in course of national assembly of the Crimean people, médjlis leaders initiated holding of «The International forum on restoration of the rights of the Crimean people» with wide participation of the international institutions. According to experts, initiating the given action, Crimean leaders try to draw thus to themselves attention of the international public, and on this background to rise own political rating in a context forthcoming parliamentary elections.
[...]
As to the 10th United States National Security Advisor, Zbigniew Brzezinski, the problem of Crimean Tatar people is one of the most complicated on the post-Soviet area and should be solved by international community. Official Kiev expressed complete support to idea of carrying out of International forum on restoration of the rights of Crimean Tatar people, fairly counting, that carrying out of such large-scale action will allow Ukraine to make utilize international experience and develop ways of decision of problems on restoration of historical justice, maintenance of rights and freedom, culture development, maintenance of language and originality of repatriated Crimean Tatar people.
The Crimean Tatars: destiny of the people in destiny of Ukraine