Shipping on the Northern Sea Route has far to go before achieving its potential, but Russia’s fleet of nuclear-powered icebreakers have been busy in the region of late.

According to Rosatomflot, the state icebreaker company, 420 vessels loaded with 5.29 million tons of cargo were escorted on the Northern Sea Route last year, up more than 100 percent from 2015. In 2015, a total of 195 ships with 2.04 million tons of cargo were escorted.

Most of this growth is attributable to the development of new industrial projects, including the Yamal liquefied natural gas installation and the Novy Port oil field. Around 120 ships visited Sabetta, the new Yamal LNG sea port on the northeastern end of the Yamal Peninsula, in 2016, most of them with assistance from Rosatomflot.

The militarization of Russian Arctic increases demand for icebreakers. Numerous shipments were in 2016 made to the new military bases on archipelagos like the Franz Josef Land, New Siberian Islands, Severnaya Zemlya and Wrangel Island.

The 50 Let Pobedy, the newest of the nuclear-powered vessels, alone escorted 99 ships between August 2016 to February 2017. When it returns from its current voyage in mid-March, the vessel will undergo a series of upgrades.

In the last part of 2016, Rosatomflot’s capacity was strained following the repair and service on the Yamal, a ship built in 1993. According to the company, the ship was back in duty in Arctic waters in February of this year.

Russia currently has a total of four icebreakers in operation and one more on the way. The Arktika, under construction in the Baltic Yard near St. Petersburg, is due to delivered later this year.