KIEV, Ukraine (AP) — Russian President Vladimir Putin on Wednesday blamed the latest standoff with neighboring Ukraine on the presidential ambitions of Ukraine's leader, as the Russian military announced it was boosting its defenses in Crimea.

Ukraine, for its part, released what it said was the exact location where its ships were fired on Sunday by Russia, showing that they were in international waters approaching Kerch Strait from the west, not from the east, as Putin suggested.

Russia and Ukraine are still reeling from their first overt military confrontation since the 1991 collapse of the Soviet Union, a clash Sunday in the Kerch Strait near Russia-occupied Crimea. Russian border guards fired on three Ukrainian ships, seizing them and their 24 crewmembers. Ukraine insists its vessels were operating in line with international maritime rules, while Russia says they had failed to get permission to pass through a Russia-controlled area.

The strait links the Black Sea with the Sea of Azov and is where Russia has built a long new bridge — the only land link between Crimea and the Russian mainland.

The incident has drawn strong criticism of Russia by the United States and its allies and has fueled fears of wider fighting in the region. It's part of the long-simmering conflict between the two countries, in which Russia annexed Ukraine's Crimean Peninsula in 2014 and supported separatists in Ukraine's east with clandestine dispatches of troops and weapons. That fighting has killed at least 10,000 people since 2014 but eased somewhat with a 2015 truce.

Putin on Wednesday broke his silence on the maritime clash, blaming it on Ukrainian President Petro Poroshenko's desire to get re-elected.

"That was a provocation which was certainly organized by the sitting officials, including the president," ahead of Ukraine's presidential election in March, Putin said.

Poroshenko's original proposal — to impose martial law in Ukraine for two months after the clash with Russia — would have meant the March president vote would have to be scrapped due to election rules. He later halved the martial law time frame to a month, which would allow the election to go ahead as planned.

The Kremlin has warned that Ukraine's declaration of martial law in areas that border Russia could re-ignite the fighting in eastern Ukraine.

Putin also claimed the Ukrainian vessels refused to communicate with Russian border guards and were in violation of the Russian territorial waters off the country's south, which, unlike the Crimean coast, is Russia's internationally recognized border. This runs counter to the claims of the Ukrainian government, which said the ships were approaching from another direction and were firmly in international waters.

Kurt Volker, the U.S. special envoy to Ukraine, told reporters in Berlin that Washington sees no reason to doubt the information from Kiev that its vessels were operating in line with international maritime rules.

Putin insisted that the Russian border guards were acting in line with the usual protocol when they decided to fire on the Ukrainian ships.

"What were they supposed to do?" he said of the Russian border guards in televised remarks Wednesday. "If they had done something differently, they should have been put on trial for that."

U.S. authorities, however, believe that there was "no conceivable justification ... for the use of force in this scenario."

Earlier Wednesday, the Russian military announced it would be boosting the defenses of the occupied Crimean peninsula with more anti-aircraft missiles in the wake of the standoff. The Interfax news agency quoted Col. Vadim Astafyev, the top Defense Ministry official in Russia's south, as saying that Russia will add one S-400 anti-aircraft missile system to the three already deployed in the peninsula.

In Ukraine, Poroshenko on Wednesday toured a military training center in the Chernihiv region, which borders Russia and is one of the areas where martial law was imposed. Speaking to reporters as smoke billowed from a nearby shooting range, the camouflage-clad Poroshenko pledged "not to allow the enemy to attack Ukraine" and announced a hike in salaries for military members.

In Crimea, nine of the captured Ukrainian seamen were expected to face court hearings in the regional capital of Simferopol later Wednesday. On Tuesday, the court ordered 15 of their compatriots to stay behind bars for the next two months.

Russia is treating the seamen as individuals who violated the Russian border, an offense that carries up to six years in prison. Ukraine insists they are prisoners of war, says some were seriously injured in the confrontation and has asked the International Red Cross to arrange a visit to see them.

Earlier this week, Russian state television broadcast separate interviews with three of the seamen, who said the Russian coast guard repeatedly warned them that they were violating Russia's territorial waters and urged them to leave. It was not clear if the men were talking under duress, but one was clearly reading from a script.

Ukraine has called that broadcast "a crime" committed by Russia.

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