Russian President Vladimir Putin on Monday acknowledged for the first time that the bloody assault on a concert hall near Moscow was executed by “radical Islamists”, but he insisted that Ukraine could still have played a role despite the Islamic State group’s claim of responsibility.

As Russians grieved, bringing flowers and candles to makeshift memorials across the country, Putin said the tragedy was likely ordered by Ukraine, a statement that shifted attention from his government’s security failure and could also help his war effort.

“The question is: Who benefited from it?” Putin said, referring to the worst attack in the capital in two decades, during a publicly broadcast meeting with government officials. “This atrocity can be just an element in a series of attempts of those who have been at war with our country since 2014,” he said, referring to the Ukrainian government.

Russian investigators have not disclosed any evidence demonstrating that the four suspects, men from Tajikistan who were migrant workers in Russia, have a connection to Ukraine.

In the news reports, Russian state television presented the location of their arrest — the Bryansk region of Russia that borders Ukraine — as evidence of Ukrainian involvement. The reports also suggested that the Ukrainian government could have hired them to mount the attack.

On Monday, Putin said, “Of course, it is necessary to answer the question, why after committing the crime the terrorists tried to go to Ukraine?” Putin said. “Who was waiting for them there?”

Ukraine denied any involvement in the attack.

Alexander Bastrykin, the head of Russia’s top investigative body, said the number of dead had grown to 139, including three children. Of those, 137 died in the concert hall and two in hospitals, he said.

Tatiana Golikova, Russia’s deputy prime minister in charge of health care, said 93 people were still hospitalized and nine were in very grave condition.

The Islamic State group has claimed responsibility for the attack. And the United States has said that the assault was the work of the Islamic State’s Afghanistan affiliate and that there was no evidence implicating Ukraine.

Ukrainian attack

A Ukrainian missile attack struck a Russian naval reconnaissance vessel and a large landing warship that Moscow captured from Kyiv during the annexation of the Crimean peninsula in 2014, Ukraine's navy said on Tuesday.

Ukraine hit the vessels during an attack on Crimea at the weekend, the navy said. The fact of that strike was already known, but the military had said it hit two other warships, the Azov and Yamal large landing ships.