One month after Russia shot at and seized three of its ships, Ukraine's martial law expired on Thursday with many still skeptical about why it was imposed and what it achieved.

The country's president, Petro Poroshenko, introduced the measure across 10 border regions last month. It was his response to what he said was an act of aggression by Moscow in the Black Sea.

Russian vessels had fired at, rammed, surrounded and then captured three Ukrainian ships headed for the contested Sea of Azov — a shallow body of water shared by the two countries near Russian-annexed Crimea.

Some two dozen sailors were detained and have yet to be released amid renewed tensions between the neighbors.

The Kremlin claimed it was a provocation by Ukraine and that its maritime borders had been violated. On Saturday Russia dismissed European demands to release the sailors and said they would be dealt with in accordance with Russian law.

Nevertheless, many saw Poroshenko's quick imposition of martial law as a political move designed to bolster his dire polling ahead of elections slated for March. Some feared he could seek to hinder or even postpone the vote altogether, as elections can't be held in Ukraine while the country is under martial law.

Under increasing pressure, the Ukrainian president let martial law expire after 30 days. He said if it weren't for the election he would have sought an extension, warning the threat from a belligerent Russia massing at his borders still existed.

"Russian threat does not go away," Poroshenko said Wednesday. He maintained the decision to introduce it was "timely and necessary."

Martial law allowed the country to boost combat readiness of its troops, increasing "their ability to respond to the threat of a full-fledged Russian invasion," according to the Ukrainian president.

His justification was that it helped relocate troops to areas vulnerable to attacks by Russia, and to enhance Ukraine's air-defense in its south and east.

But many people didn't buy it. Ukraine has suffered far worse crises than the maritime standoff last month. Why not impose martial law during the annexation of Crimea in 2014, these critics asked, or at any time during the ensuing conflict with Russia-backed rebels that's claimed 10,000 lives in the east of Ukraine?

"The country has been living in a de facto state of war for over four years," said Dmitry Razumkov, a political analyst with Kiev-based Ukrainian Politconsulting Group. "If you follow this logic, this should have been done way sooner."

Part of Poroshenko's reasoning was that Russia might be preparing for an attack. But Ukrainians have been told this for years, Razumkov points out. So why impose martial law now?

Mark Galeotti, a senior non-resident fellow at the Institute of International Relations Prague, agrees it was down to politics rather than security.

The introduction of martial law was "a political gambit born of Poroshenko's desperation to look tough on national security" rather than a genuine defense measure, Galeotti said. "It is hard to see any meaningful or lasting military benefit from martial law."

Although 58 percent of Ukrainians believe that Russia committed "an act of military aggression" against Ukraine last month; even more — 60 percent — opposed the imposed martial law, according to pollster Rating Group Ukraine.

This combination of opposition at home and concern in the West meant that this ploy was "a non-starter" from day one, Galeotti said.

Others disagree, maintaining that imposing martial law was a necessary show of force to Russia.

"For Ukraine, if they do not respond to Russian actions, then the Russians may keep pushing," said Jack Watling, a research fellow at London's Royal United Services Institute think tank.

"Martial law was an attempt to demonstrate that Ukraine could and would respond, without provoking further escalation. In that sense it succeeded and did not need to remain in effect."

That's not to say that the situation is over.

Oleksandr Turchynov, secretary of Ukraine's National Security and Defense Council, warned earlier this month that his country would once again attempt to send warships back to the Azov Sea.

On Wednesday, Russian Foreign Ministry spokeswoman Maria Zakharova told state-run news agency TASS that she hoped western countries can stop Ukraine from engaging in "a new provocation" that could lead to an escalation.