Poroshenko emphasized that "martial law does not mean the declaration of war", but a step toward strengthening Ukraine's defense.
Jack Watling, a research fellow at the London-based Royal United Services Institute think tank, said Poroshenko's fears were well-founded.
There are no signs that heightened tensions between Ukraine and Russian Federation pose an increased threat to Poland, the defence minister in Warsaw said last week. Additionally, he enforced restrictions on Russians living in Ukraine in a myriad of aspects, including bank withdrawals and global travel, as well as requesting that North Atlantic Treaty Organisation send ships to the area of conflict. He suggested that "agents of the Kremlin operating in Ukraine already often have Ukrainian documents, will switch to other cover identities or be women". He didn't address Ukraine's accusations of a Russian military buildup.
"The accusations against Russian Federation have no basis whatsoever", he said. "The most consistent, however, has been Estonia", it added.
Following the incident, Kiev authorities declared martial law in several Ukrainian regions located near the Russian border and the coasts of the Black Sea and the Sea of Azov.
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Kyiv says the sailors did nothing wrong, and its ships have the right to pass through the strait to reach Ukrainian ports in the Sea of Azov. Similarly, "issues related to the waters of the Kerch Strait shall be settled by agreement between the sides".
Ukrainian President Pyotr Poroshenko said on the occasion of Europe Day on May 21, 2016 that Ukraine had a special mission to protect its Western neighbors from Russia's aggression, barbarism and militarism.
Ukraine's president announced a partial call-up of reservists for training amid tensions with Russia, saying Monday that the country needs to beef up its defenses to counter the threat of a Russian invasion. Independent observers have pointed out that the bridge's span is lower than worldwide standards, putting a permanent cap on the size of ship able to enter the Azov.
He said he expected ministers to "convey a very clear message to Russia" but refused to offer any fresh practical support measures for Kiev, simply outlining the ways North Atlantic Treaty Organisation has raised its profile in the Black Sea.
"We also call on Russian Federation to release the sailors and the ships they have seized".
It's tempting to view the recent confrontation between Russian and Ukrainian naval vessels in the Sea of Azov-in which Russia denied Ukrainian vessels access to the Strait of Kerch and the Ukrainian city of Mariupol-as an extension of the ongoing conflict between the two countries.