US Secretary of State Antony Blinken warned in an interview Sunday of "consequences" if Russia acts "aggressively" towards Ukraine, amid rising alarm over a Russian troop build-up on the border of the former Soviet republic.
"I have to tell you I have real concerns about Russia's actions on the borders of Ukraine," Blinken told NBC's "Meet the Press." "That's why we're in very close contact, in close coordination, with our allies and partners in Europe. All of us share that concern."
"President Biden's been very clear about this. If Russia acts recklessly, or aggressively, there will be costs, there will be consequences," Blinken said.
In recent weeks fighting has intensified between Ukraine's army and pro-Russian separatists in the country's east, with signs of a Russian troop build-up in the region raising concerns of major escalation in the long-running conflict.
Ukraine has accused Russia of amassing thousands of military personnel on its northern and eastern borders as well as on the annexed Crimean peninsula.
The Kremlin, which has not denied the troop movements, said Sunday it was not moving towards war with Ukraine -- but also that it "will not remain indifferent" to the fate of Russian speakers in the conflict-torn region.
The White House this week said the number of Russian troops at the border with Ukraine was now greater than at any time since 2014, when the conflict erupted after Russia's annexation of Crimea from Ukraine.
The conflict in Ukraine's east has claimed more than 13,000 lives and turned into a nagging problem in Moscow's relations with the West.
Fighting has subsided in the past few years but a diplomatic solution to settle the eastern regions' status has stayed out of reach.
Crimea is still recognized as part of Ukraine by the United Nations, and Kiev vows to one day win it back.
Biden, who previously oversaw Washington's policies on Ukraine, is viewed as a strong ally by Ukrainians and his top diplomat Blinken, in talks this week with his French and German counterparts, agreed on supporting Ukraine against "Russian provocations".