Russia has deployed a new division of S-400 surface-to-air missiles in Crimea, Russian news agencies reported, in an escalation of military tensions on the Crimean peninsula.
- The missiles will control the airspace over the border with Ukraine
- The S-400 can bring down airborne targets within a 400km range
- Fresh US sanctions against Russia are expected within weeks
The US said in December it planned to provide Ukraine with "enhanced defensive capabilities", including Javelin anti-tank missiles.
Washington is expected to impose fresh sanctions against Moscow next month for alleged meddling in the 2016 US presidential vote, further straining relations between the two superpowers.
Moscow's latest deployment represents the second division armed with S-400 air defence systems on the peninsula, after the first was deployed in the spring of 2017 near the port town of Fedosia.
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 defence 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 defence ministry says the S-400 systems, known as "Triumph", can bring down airborne targets at a range of 400 kilometres and ballistic missiles at a range of 60 kilometres.
They were first introduced to the Russian military's arsenal in 2007, the ministry said.
Russia braces for new US sanctions
Deputy Foreign Minister Sergei Ryabkov told local media the expected US sanctions, which may be imposed as soon as early February, are an attempt to influence Russia's domestic affairs.
"We see this as yet another attempt to influence our internal situation, especially ahead of the presidential election," Mr Ryabkov said.
Russia will hold its next presidential vote on March 18 when President Vladimir Putin is widely expected to win another six-year stint.
Russia has repeatedly denied any involvement in the 2016 US elections that put Donald Trump in power.
Mr Ryabkov told Tass news agency he expects the United States to present two anti-Russian reports with the sanctions.
One of the reports would likely extend the number of Russian officials and companies on the sanctions list, while the other would analyse whether sanctions so far have proved to be effective, Mr Ryabkov said.
After the first round of sanctions in 2014 for annexing Crimea, Russia retaliated by banning food imports from signatory countries.
In August last year, Mr Trump grudgingly signed into law a new package of sanctions that Congress had overwhelmingly approved, which also limited Mr Trump's own ability to lift any sanctions against Russia.
He criticised the legislation as having "clearly unconstitutional" elements.
The new round of US sanctions could possibly include a ban on the purchase of Russian treasury bonds.