Ukraine again challenges Russia for separation, this time at sea - and looses ships
https://www.breitbart.com/europe/2018/11/25/ukraine-considers-declaring-martial-law-after-apparent-defeat-in-russia-naval-skirmishes/
The Ukrainian president will ask his parliament to consider enacting martial law after three Ukrainian navy ships were fired upon and captured in the Black Sea on Sunday.
Following its fragmentation in the 13th century, the territory was contested, ruled and divided by a variety of powers, including Lithuania, Poland, Austria-Hungary, the Ottoman Empire and Russia. A Cossack republic emerged and prospered during the 17th and 18th centuries, but its territory was eventually split between Poland and the Russian Empire, and finally merged fully into the Russian-dominated Soviet Union in the late 1940s as the Ukrainian Soviet Socialist Republic.
Since 1991 Ukraine politicians have claimed they do not wish to be part of Russia.
HOWEVER, Russia claims the issue is a "grab" of a large natural gas deposit at the sea Russia has no intention of "letting go of".
(were ukraine to disclaim ownership of that Russia might reconsider - but ukrainian politicians are not disclaiming it. other states trying to succeed in past also had large ore deposits russia had invested to be developed / mined)