Ukraine officials say second stage of anti-terrorist operation under way in east as helicopter shot down (UPDATES, VIDEO)

In a message posted to Facebook, Arsen Avakov squashed reports that the mission had been suspended, saying it was still on. “ATO (anti-terrorist operation) continues. Terrorists should beware around the clock. Civilians have nothing to fear,” he said.

Serhiy Pashinskiy, the Ukrainian president’s chief of staff, reiterated his remarks, saying that the operation will continue and that the goal is to encircle the city of Sloviansk.

“Twenty minutes ago, Ukrainian special units began the second stage (of the anti-terrorist operation), which consists in that we have made a decision to fully blockade the city of Sloviansk to prevent help from reaching it,” he said.

Earlier, Vasyl Krutov, the head of the Ukrainian Security Service’s Anti-Terrorist Center, said participants in the counter-terrorist operation would not storm Sloviansk because it would lead to casualties among locals.

Sloviansk, Donetsk Oblast, home to some 120,000, was seized by armed pro-Russian militants more than a week ago. They have set up checkpoints around the city, holed up in its security services and city administration buildings and taken several persons as hostages, including journalists. One, American Simon Ostrovsky, was released on April 24 after being beaten and held for two days. Others are still being held and their condition is unknown.

A senior security official speaking on the condition of anonymity told the Kyiv Post on April 24 that Kyiv’s anti-terror operation had been halted after a morning offensive fell short of its goal of purging the pro-Russian militants from Sloviansk. The government paused to reformulate its plan based on the latest intelligence from the eastern border, which showed heavy Russian troop movements, the official said.

Moscow confirmed on April 24 that its military was conducting exercises at its western border. Ukraine’s Defense Minister Mykhailo Koval said on April 25 that Russian troops had come within one kilometer of Ukrainian territory during the war games, but stressed that they had not crossed the border. Should they do so, Ukraine would be prepared to respond, he said.

“The Armed Forces of Ukraine are ready to repel any aggression. They (the Russian troops) have not violated the borders. Yesterday there were some maneuvers near the state border. We took the appropriate steps in response,” Koval said.

Meanwhile, a military helicopter exploded at a Ukrainian airfield in Kramatorsk, 15 kilometers from Sloviansk, after being shot at. Pro-Russian militants claimed responsibility for shooting down the helicopter, the Russian state-run news agency RIA Novosti reported.

Witnesses reported hearing explosions from the base around 11:30 a.m. Dmitry Tymchuk, a defense expert and director of the Center of Military and Political Research in Kyiv, told reporters that the Mi-8 helicopter had exploded upon take-off and the pilot managed to escape with minor injuries.

Krutov said the helicopter was fired upon, causing it to blow up. “Yes, indeed, a helicopter at the airfield in Kramatorsk was shot by a single sniper bullet. The shot was made at the fuel tank. Due to this there was an explosion,” he told reporters.

Pro-Russian militants had previously made an attempt to seize the airfield but were repelled by Ukrainian forces. Like in Sloviansk, militants have besieged the city and captured its police and administration buildings.

Photographs and video shared on social media showed plumes of black smoke billowing into the sky above the Kramatorsk airfield.

Separately, overnight on April 25 in Odesa several persons were injured in a blast at a pro-Ukrainian checkpoint near the border with Moldova’s breakaway territory Transnistria, when unidentified persons tossed  from a car an explosive device toward guards at the checkpoint. The severity of their injuries is still unknown.

Kyiv Post editor Christopher J. Miller can be reached at miller@kyivpost.com, and on Twitter at @ChristopherJM.