Twenty-four Ukrainian sailors were arrested by Russia in November 2018 because three Ukrainian Navy vessels violated the Russian-Ukrainian border when seeking to transit the Kerch Strait.
Recurring pro-Kremlin disinformation about the November 2018 Kerch incident. Russia has seized Ukrainian vessels and their crews and fired shots at them, wounding several Ukrainian servicemen. The EU has urged Russia to release the captured crew.
The Kerch Strait and the Sea of Azov, as addressed by the 2003 bilateral agreement between Ukraine and Russia are defined as internal waters of both Russia and Ukraine. The agreement gives both parties the power to inspect suspicious vessels. Furthermore, both the 2003 bilateral agreement and UN Convention on the Law of the Sea provide for the freedom of navigation. See a similar case here.