Which weapons has Russia moved to Kaliningrad?
Bastion land-based coastal-defense missile launchers: In October, Russia beefed up its anti-shipping defenses in Kaliningrad with these launchers. Since then, it has used them as an offensive weapons against rebel positions in Syria. According to IHS Jane's 360, the supersonic missiles fired from the Bastion have a range approaching 200 miles. In a conflict, they could be used against NATO ships trying to reach the Baltic states.
S-400 land-based air-defense missiles: Russia has already installed these state-of-the-art missile systems to protect its air base in Syria. The S-400 can simultaneously track and strike a number of aerial targets at once at ranges of up to 250 miles. In Kaliningrad, S-400s would be capable of targeting NATO aircraft and missiles over most of the Baltic region.
Iskander-M mobile nuclear-capable land-based ballistic missile system: The Iskander-M is a mobile short-range ballistic missile system with an official range of just more than 300 miles. That complies with the limits set by the landmark 1987 Intermediate-range Nuclear Forces Treaty signed by the United States and the Soviet Union. Iskander is extremely mobile and hard to detect and has superior accuracy.
That sounds bad. What could be worse?
Longer-range, nuclear-capable land-based ballistic missiles: The United States accuses Russia of developing land-based ballistic missiles with a range much greater than allowed by the INF treaty — some military estimates suggest that Russia has tested a missile that could reach major European capitals. The whole point of the INF treaty was to eliminate the threat of rapid nuclear escalation posed by hidden launchers carrying devastating weapons a short flight time. But Moscow denies the allegation and says that it is the United States that is breaking the treaty with illegal intermediate missiles of its own.