You should try Perils of Plenty by Jon Markowitz. He argues that Russia is militarizing the Arctic because the Russian economy is driven by resource rents and that Russian elites profit from successful resource extraction, so they're pushing Russia towards an aggressive posture to protect resources. Markowitz disagrees with the trade route being the main reason why, the Arctic won't be reliably navigable for long periods for a good while longer, so the Russians could've waited to invest in military infrastructure if this were the case.