The crew on a nuclear-powered Russian military submarine prevented a “planetary catastrophe,” according to a top naval officer who spoke at the funeral for the 14 sailors who died during a fire on the vessel.

Captain Sergei Pavlov, an aide to the commander of Russia’s navy, said Sunday the sailors “saved the lives of their colleagues, saved the vessel and prevented a planetary catastrophe.”

Dmitry Peskov, a Kremlin spokesman, said there were no signs the incident could have caused a larger catastrophe. “As for the reactor, there are no problems with that,” he said.

After days of secrecy about the incident, Russia confirmed late last week that the research vessel was nuclear powered, though it has refused to say what type of craft was involved. The Kremlin said that information was “absolutely classified.”

The craft is believed to be part of a secret nuclear-submarine project known as Losharik, according to reports, and was used to target underwater communications and cables. Russia has said the submersible was used to explore the sea bed.

Defense Minister Sergei Shoigu said the nuclear reactor on board had been completely sealed off from the fire.