Russia’s error-prone Bulava intercontinental ballistic missile has suffered its eighth failure in 12 tests, the Defence Ministry said on Thursday, dealing another blow to Kremlin hopes that the sea-based weapon would become a cornerstone of its nuclear arsenal.

Officials had hoped military contracts for the submarine-launched missile could be negotiated next year, but the high-profile botches look likely to derail those plans.

The Defence Ministry’s statement announcing the latest failure, which it said occurred after Wednesday’s launch from the White Sea just east of Scandinavia, came amid speculation about the origin of mysterious spiralling lights over northern parts of Norway. Photographs and amateur video footage of the lights have been circulating on the Internet since Wednesday.

The ministry said it did not know whether the lights were the Bulava, which can accommodate multiple nuclear warheads and has a range of 5,000 miles (8,000 kilometers).

“The first two stages of the rocket worked as they should have, however, in the third and final stage of the flight a technical error occurred,” the statement said. “According to tests, the third stage’s engine was unstable.”

Despite the repeated failures - which look set to torpedo plans to finish testing this year - Russian leaders have boasted about the Bulava’s ability to penetrate missile defences and have described it as a key part of the military’s future nuclear arsenal.

Officials have insisted the Bulava’s design is fine and have blamed its failed tests on manufacturing flaws resulting from post-Soviet industrial degradation. They have said it’s difficult to control the quality of all the parts supplied by the 650 subcontractors involved in the programme.