Delays plaguing the launch of the Arktika nuclear icebreaker, billed to be Russia’s largest to date, have prompted a number of lawsuits against the ship’s builder as frustrations mount over a series of technical faults thwarting the vessel’s scheduled release.

According to the Barents Observer, which cites industry news portals, Atomflot, Russia’s nuclear icebreaker headquarters, has filed three multi-million dollar lawsuits against the Baltic Shipyard, the St Petersburg-based shipbuilder that has forged most of the country’s icebreaking muscle.

Details of the lawsuits are sketchy. But the Barents Observer reports that the suits seek nearly $13.5 million in damages over faulty ship systems and overdue part deliveries, all of which have caused the icebreaker project to overshoot its 2017 deadline.

The latest of these mishaps involves a 300-ton electric propulsion engine that failed during the Arktika’s sea trials in February, crippling one of the vessel’s three propeller systems. While the breakdown is not related to the Arktika’s nuclear propulsion system, it was nonetheless an embarrassing setback that will ultimately require the engine to be entirely replaced.

Russian media now suggest that the Arktika won’t be repaired before 2021.

A new series of upgraded nuclear icebreakers are central component of a Kremlin strategy to keep Arctic sea routes open on a year-round basis. Russia has since Soviet times maintained the world’s largest stable of these vessels. But many have been decommissioned in recent years, and Moscow has embarked on renewing the fleet.

The target of this effort is the Northern Sea Route, a 5,600-kilometer sea artery joining Europe to Asia, whose frozen shores are laden with fossil fuels and mineral deposits.

To stimulate its development, President Vladimir Putin ordered in 2017 that cargo volumes along the passage reach 80 million tons by the middle of this decade – more than double current volumes.

The Arktika, and two other icebreakers in its class – the Ural and the Sibir – are meant to lead the way. Each vessel measures up to 173 meters in length and all are powered by twin RITM-200 nuclear reactors, which deliver a combined 175 megawatts of power – making them the most powerful civilian vessels in the world.

The hulls of the Arktika’s sister vessels, the Ural and the Sibir, have also been floated by the Baltic Shipyard. Two more vessels in the line, which have yet to be named, are scheduled to launch in 2024 and 2026, according to a $1.47 billion government tender published last summer.

The ships, which are designed to operate both in deep waters and along the Arctic’s craggy and shallow coastline, are envisioned as Moscow’s battering ram through the ice as it seeks to boost shipping along the Northern Sea Route.

The passage lops days off conventional shipping arteries like the Suez Canal. But icebreaking vessels are still needed to keep trade lanes open for cargo convoys for much of the year – a service for which Moscow charges shippers a hefty toll.

Atomflot has filed its suits against the Baltic Shipyard in Moscow’s Arbitration court, the Barents Observer reports. In turn, the shipyard is suing one of its own suppliers – the giant Kirov Plant in St Petersburg, which manufactures heavy machinery.

The Arktika’s rollout has face previous delays. In March of 2017, turbines produced by a Ukraine-based manufacturer were held up by military tensions between Moscow and Kiev.