The President of Ukraine Petro Poroshenko and the US planned the Kerch strait confrontation. The US probably approved Poroshenko’s plan in order to use the incident against the Nord Stream 2 pipeline project.
There is no connection between the Kerch strait clash and Nord Stream 2 pipeline project.
On November 25 border patrol boats belonging to Russia’s FSB security service seized two small Ukrainian armoured artillery vessels and their crews after shooting at them, wounding several Ukrainian servicemen. Russia argued that they were in Russian waters.
However a bilateral treaty between Russia and Ukraine, signed in 2003 and ratified by Russia in 2004, governs the use of the Kerch strait and the Sea of Azov, which in the treaty is considered to be the “internal waters” of both Russia and Ukraine.