Martial law came into force across a large swath of Ukraine on Nov. 28, following a clash at sea that Kyiv called an "act of aggression" by Moscow and Russian President Vladimir Putin claimed was ploy to boost his Ukrainian counterpart's popularity ahead of an election in March.
Ukraine introduced martial law in 10 of its 27 regions -- including all of those that border Russia or have coastlines -- after Russian coast-guard craft rammed and fired on three Ukrainian Navy vessels off the Black Sea peninsula of Crimea on Nov. 25 before seizing the boats and detaining 24 crew members, six of whom were wounded.
In two days of hearings, courts in Russian-controlled Crimea ordered all 24 to be held in custody for two months pending possible trial, defying calls from Kyiv and the West for their immediate release and also signaling that the Kremlin wants to cast the incident as a routine border violation rather than warfare at sea.
The detention period can be extended, and the Ukranians face up to six years in prison if convicted on charges of illegal border crossing.
In his first public comments on the incident that increased already high tensions between Kyiv and Moscow and sparked concerns of a widening of the simmering war between Ukrainian government forces and Russia-backed separatists in eastern Ukraine, Putin reiterated Russia'a accusation that the Ukrainian boats trespassed in Russian waters -- a claim Kyiv has denied.
"It was without doubt a provocation," Putin told a financial forum in Moscow.
He claimed that the confrontation was orchestrated by Ukrainian President Petro Poroshenko, who opinion polls indicate faces an uphill battle in his expected bid for a second term in an election now officially scheduled for March 31.
"It was organized by the president ahead of the elections," Putin said, adding that Poroshenko "is in fifth place, ratings-wise, and therefore had to do something. It was used as a pretext to introduce martial law."
Putin claimed that the Ukrainian "military vessels intruded into Russian territorial waters and did not answer" the Russian coast guard. "What were they supposed to do?"
"They would do the same in your country. This is absolutely obvious," he said, responding to a question from a foreign investor at the forum.
While laying the blame squarely on Ukraine, Putin -- whose country could face fresh Western sanctions over the clash -- also sought to play it down, saying it was nothing more than a border incident and calling martial law an exaggerated response.
Opinion polls in Ukraine suggest that Poroshenko faces an uphill battle in his expected bid for a second term in a presidential election scheduled for March 31.
Some Kremlin critics suspect that it was Putin who orchestrated the clash, in an attempt to bolster his own approval rating amid anger in Russia over plans to raise the retirement age.
In earlier comments at the same conference, Putin said he hopes he will meet with U.S. President Donald Trump on the sidelines of a G20 summit later this week in Argentina, as planned.
Trump cast doubt on the meeting on November 27, telling The Washington Post that he might not meet with Putin as a result of the confrontation between Russia and Ukraine, adding: "I don't like that aggression. I don't want that aggression at all."
The Ukrainian parliament late on November 26 voted to impose martial law for 30 days in the provinces that Poroshenko said are the most vulnerable to "aggression from Russia."
The 10 provinces all border Russia or Moldova's breakaway Transdniester region, where Russian troops are stationed, or have coastlines on the Black Sea or the Sea of Azov close to Crimea.
Among other things, martial law gives Ukrainian authorities the power to order a partial mobilization, strengthen air defenses, and take steps "to strengthen the counterintelligence, counterterrorism, and countersabotage regime and information security."
It is the first time Ukraine has imposed martial law since Russia seized Crimea in March 2014 and backed separatists fighting Kyiv's forces in a war that erupted in the eastern provinces of Donetsk and Luhansk the following month.
Those moves, which prompted the United States, the European Union, and others to impose sanctions on Russia, followed the downfall of a Moscow-friendly Ukrainian president who was pushed from power by a pro-European protest movement known as the Maidan.
While Russian forces occupied Crimea before the takeover and are heavily involved in the war in eastern Ukraine, according to Kyiv and NATO, the clash in the Black Sea near Crimea was the first case in which Russia has acknowledged its military or law enforcement forces have fired on Ukrainians.
Before Putin made his comments, the Kremlin called the introduction of martial law a "reckless" act that "potentially could lead to the threat of an escalation of tension in the conflict region in the southeast" of Ukraine.
Meanwhile, the Russian military said it will bolster the defenses of Russian-controlled Crimea by add one S-400 surface-to-air missile system to the three already deployed there."
The new air-defense missile system will soon be put on combat duty to guard Russian airspace," Colonel Vadim Astafyev said. State-run news agency RIA Novosti said the system will be operational by the end of the year.
Moscow claims that Crimea is part of Russia, but the overwhelming majority of countries reject that and still consider it to be part of Ukraine.
Poroshenko said that Russia's actions threatened to lead to a "full-scale war" and accused Moscow of mounting a major buildup of forces near Ukraine.
"The number of [Russian] units that have been stationed along our entire border has increased dramatically," Poroshenko said in a television interview late on November 27, adding that the number of Russian tanks has tripled. Russia has not commented.
The clash in waters near Crimea was by far the biggest confrontation at sea after more than four years of war between Kyiv and Russia-backed separatists in eastern Ukraine, where more than 10,300 civilians and combatants have been killed.
It followed months of growing tension over the waters in and around the Kerch Strait, where Russia opened a bridge leading to Crimea in May.
The strait is the only route for ships traveling between the Black Sea and the Sea of Azov, where Ukraine has several ports.
In comments to The Washington Post published on November 27, Trump said he was considering canceling his scheduled meeting with Putin on the sidelines of a Group of 20 (G20) summit in Buenos Aires on November 30-December 1.
Trump told The Washington Post he was waiting for a "full report" from his national-security team about the incident.
"That will be very determinative," Trump told The Washington Post. "Maybe I won't even have the meeting...I don't like that aggression. I don't want that aggression at all."
Putin's spokesman, Dmitry Peskov, said on November 28 that "preparations are continuing, the meeting was agreed."
"We don't have any other information from [U.S. officials]," he said when asked about Trump's comments.
Meanwhile, U.S. State Department spokeswoman Heather Nauert urged European states to do more to support Ukraine and said Washington wants to see tougher enforcement of sanctions against Russia.
European Union leaders said they were considering ratcheting up sanctions on Russia for illegally blocking access to the Sea of Azov over the weekend and because of its defiance of calls to release the Ukrainian crew members.
On November 27, Russian courts in the Crimean cities of Simferopol and Kerch ordered 15 of the Ukrainians to be held in custody for two months. Hearings for the other nine on November 28 produced the same result.
The mother of detained sailor Andriy Eyder, Viktoria Eyder, told RFE/RL's Ukrainian Service in the Black Sea port city of Odesa that her son was "wounded and is hospitalized in Kerch."
The court rulings put the sailors in a situation similar to that of several Ukrainians, including film director Oleh Sentsov, who are being held in Russian prisons and jails for what Kyiv and Western governments say are political reasons.
With reporting by RFE/RL's Ukrainian Service, the Crimean Desk of RFE/RL's Ukrainian Service, AFP, AP, Reuters, dpa, BBC, Interfax, and RIA
This article originally appeared on Radio Free Europe/Radio Liberty. Follow @RFERL on Twitter.