Also significant is the build-up of Russian surface-to-surface and surface-to-air missile assets in the region. Dmitry Gorenburg of the Centre for Naval Analysis (CNA) has noted that: "Russia's expanded military footprint in Crimea allows it to carry out a range of operations that it was not capable of prior to 2014. The deployment of S-400, Bastion, and Bal missiles allows the Russian military to establish an anti-access/area-denial zone (A2/AD) covering almost all of the Black Sea. By using a combination of ground-based and ship-based missiles, backed with strong electronic warfare capabilities, the Russian military can inhibit military movement into the Black Sea and deny freedom of action to an opponent if it does make it into the theater. The long-range sea-, air-, and ground-launched missiles deny access, while shorter-range coastal and air defense systems focus on the area denial mission. The result is several interlocking air defense zones". Ongoing technological upgrades of this already robust SAM network are planned for the 2020s. Others, such as Michael Kofman of CNA, argue that while there is no A2/AD doctrine or term in Russian military strategy, Russian forces nevertheless are organized at an operational and strategic level to deploy a wide range of overlapping defensive and offensive capabilities that extend beyond just one theatre of operations like the Black Sea.