'A few NATO vessels can come and be present in the Black Sea because this is the point of global security. And we will discuss which nation will present these frigates but they definitely need to be NATO [countries] to not to allow Russia to act like that anymore', Poroshenko said.
Earlier in the day, Russian President Vladimir Putin called the incident a provocation prepared in advance, as well as a pretext to introduce martial law in Ukraine.
Prior to that, Poroshenko signed a decree to impose martial law in a number of Ukrainian regions, following an incident on Sunday when three Ukrainian vessels were seized by Russia in the Black Sea after breaching the Russian maritime border.
On Sunday, Ukraine's Berdyansk and Nikopol gunboats and the Yany Kapu tugboat crossed the Russian maritime border. According to Russia's Federal Security Service (FSB), the vessels sailed toward the Kerch Strait, an entrance to the Sea of Azov, and were seized by Russia after failing to respond to a demand to stop.