President Vladimir Putin has warned that no country can "intimidate" or "isolate" Russia.
Putin, speaking in Moscow on December 20, said such attempts had repeatedly been made over the centuries. He said that currently "open calls are being made to make Russia pay dearly for its independent stance, for the support of its compatriots, for Crimea, for Sevastopol, and for our mere existence."
But Putin, in an address to mark the national holiday of Employees and Veterans of Russia's Security Forces said: "Of course, no one will be able to intimidate us, or contain and isolate Russia. No one has ever been able to and no one ever will."
Putin called for improvement of Russia's secret services to tackle "modern challenges and threats" amid tensions with the West over the Moscow's role in the Ukrainian crisis.
Putin said the most important tasks for Russia's intelligence services were the fight against global terrorism and the prevention of "any attempts of foreign special services to deal a blow to Russia and her political and economic interests."
Russia's economy is expected to slip into recession next year because of Western sanctions and the falling price of oil.
Earlier on December 20, the Russian Foreign Ministry said that the new sanctions won't push Russia to give up Crimea since it is a "historic and integral part of Russia."
The ministry referred to Cuba, where it took the United States half a century to restore diplomatic relations, and said it was prepared to wait as long as necessary for Washington to relent.
U.S. President Barack Obama on December 19 called on Russia to end its annexation of Crimea and announced new measures prohibiting U.S. companies and individuals from exporting or importing any goods, services, or technology to or from Crimea.
Obama also authorized the Treasury Department to impose sanctions on individuals and companies operating in the region.
The Treasury Department announced 17 names and seven entities blacklisted under the order.
The move comes one day after the European Union banned investment in Crimea.
Crimea has been under de facto Russian control since March, after Russian-backed forces took the peninsula from Ukraine.
The Russian Foreign Ministry also said on December 20 that Moscow planned to work out measures in response to new U.S. and Canadian sanctions against Russia.
Foreign Ministry spokesman Aleksandr Lukashevich said, "We recommend that Washington and Ottawa think about [the] consequences of such actions. And we will explore response measures."
Obama signed legislation on December 18 implementing broad new sanctions on Russia over its activities in Ukraine but said that he would not use the authority at this time.
The law authorizes new sanctions against Russia's defense and energy industries, including the arms exporter Rosoboroneksport, and investors in its high-tech oil projects.
The legislation also authorizes -- but does not technically require -- $350 million of defense articles for Ukraine's military, including antitank and antiarmor weapons, ammunition, and surveillance drones.
Canadian Prime Minister Stephen Harper on December 19 announced another round of economic and travel sanctions on 20 Russian and pro-Russia Ukrainians, as well as measures against the country's oil and natural-gas industry.
Harper warned that "the Putin regime has continuously violated the territorial integrity, sovereignty and independence of Ukraine."
With reporting by Interfax and AFP