But Azov sea belongs to Russia why would Ukraine try and enter it>?
Both Russia and Ukraine share coast lines on Azov Sea. However Ukraine's access out of Azov Sea, and into the Black Sea, is truncated by the natural topography of Crimean Peninsula connecting with Novorossysk (hope I spelt that correct) Peninsula at a focal point, where the Russian Federation has built the Bridge (an engineering marvel, I might add). Ukraine has the right to access the Azov Sea and Black Sea for commerce, yes. However Ukraine has no trading port in the Azov Sea. Which is why the Russian Federation is blocking the Ukrainians, because the latter is attempting to assert itself (futile effort) there, at the behest of US-NATO. They know all too well, that they cannot challenge the Russian Federation for naval supremacy in the Black Sea, so long as Russia has Crimea and Russia has consolidated itself in Crimea, both militarily and economically.
Ukraine would've have been better off having cordial relations with Russia and would have flourished in both trade and militarily strengthened itself, had Ukraine continued to expand trade political alliance with Russia. Instead, Ukraine has now trapped itself in a vicious grip. Making policies which deliberately target Russian speaking Ukrainians, banning the Russian language, igniting internal conflict in the Donbass region. Any one see a familiar pattern forming here? Lost Crimea, because Ukraine's revolt was stupid enough to fall for the old Western "democracy" carrot. They're cut off from Russian Gas supplies, because they started siphoning off supplies meant for Europe. It's turned out to be quite a mess and such is always the case wherever US-NATO get involved in. You've got to be blind as a bat not to see Iraq, Libya, Syria, Afghanistan, Yemen, Somalia, Sudan, Albania & Kosovo.
So no, Azov Sea doesn't belong to Russia, but that is exactly why "they" are using against Russia and they're using their favored yuppie-pawn, Ukraine to undermine Russian Naval presence in the Black Sea. If Russia doesn't have dominant presence in the Black Sea, then no access to Mediterranean Sea and if Russia has no direct access (proximity) to the Mediterranean Sea. Then you get another Libya and Iraq, in Syria!! And once Syria, Iraq are "Balkanized" the door is wide open for Israel to run rampant in the Middle East, like a rabid dog.
