Russia deployed a new division of S-400 surface-to-air missiles in Crimea on Saturday, Russian news agencies reported, in an escalation of military tensions on the Crimean peninsula.

Russia annexed Crimea from Ukraine in 2014, triggering economic sanctions by the European Union and United States and a tense standoff in the region.

The U.S. said in December it planned to provide Ukraine with “enhanced defensive capabilities,” which officials said included Javelin anti-tank missiles.

Moscow’s latest deployment represents the second division armed with S-400 air defense systems on the peninsula, after the first in the spring of 2017 near the port town of Feodosia.

The new division will be based next to the town of Sevastopol and will control the airspace over the border with Ukraine, the RIA news agency reported.

The new air defense system, designed to defend Russia’s borders, can be turned into combat mode in less than five minutes, Interfax news agency quoted Viktor Sevostyanov, a commander with Russia’s air forces, as saying.

Russia’s defense ministry says the S-400 systems, known as “Triumph,” can bring down airborne targets at a range of 400 kilometers and ballistic missiles at a range of 60 kilometers.

They were first introduced to the Russian military’s arsenal in 2007, the ministry said.