But was Putin really the provocateur in Sunday's naval clash outside Kerch Strait, the Black Sea gateway to the Sea of Azov?

Or was the provocateur Ukrainian President Petro Poroshenko?

First, a bit of history.

In 2014, after the pro-Russian regime in Kiev was ousted in a coup, and a pro-NATO regime installed with U.S. backing, Putin detached and annexed Crimea, for centuries the homeport of Russia's Black Sea fleet.

With the return of Crimea, Russia now occupied both sides of Kerch Strait. And this year, Russia completed a 12-mile bridge over the strait and Putin drove the first truck across.

The Sea of Azov became a virtual Russian lake, access to which was controlled by Russia, just as access to the Black Sea is controlled by Turkey.

While the world refused to recognize the new reality, Russia began to impose rules for ships transiting the strait, including 48 hours notice to get permission.