US President Joe Biden has held rare talks by video link with his Russian counterpart Vladimir Putin, amid tensions on Ukraine's eastern frontier.
After opening moments shown on video footage, the US and Russian leaders then continued talks behind closed doors for about two hours. Photo: AFP / Mikhail Metzel / Pool / Sputnik via AFP
Biden voiced "deep concerns" over the massing of Russian troops near Ukraine, threatening "strong economic and other measures", Washington said.
Moscow earlier said talks were needed as tensions were "off the scale".
Russia has moved thousands of troops to the border, but insists it has no intention of attacking Ukraine.
It wants guarantees Ukraine will not join Nato, but Western powers say Kyiv's sovereignty should be respected.
The talks began at 10.07am US Eastern time, the White House said.
They were held on a secure video link set up under previous administrations but never used before, Russian news agency Tass said.
Video footage of the opening moments showed friendly greetings between the US and Russian leaders. The talks then continued behind closed doors, lasting about two hours.
Putin held the talks from his residence in the southern resort of Sochi, according to Tass.
In a statement after the talks, the White House said: "President Biden voiced the deep concerns of the United States and our European allies about Russia's escalation of forces surrounding Ukraine and made clear that the US and our allies would respond with strong economic and other measures in the event of military escalation.
"President Biden reiterated his support for Ukraine's sovereignty and territorial integrity and called for de-escalation and a return to diplomacy."
The White House said the two presidents also discussed "the US-Russia dialogue on strategic stability, a separate dialogue on ransomware, as well as joint work on regional issues such as Iran".
Biden and Putin last met in person in Switzerland in June, but made little progress other than to agree to send their ambassadors back and begin a dialogue on nuclear arms control.
In a conference call on Monday night, the White House said the leaders of the US, UK, France, Germany and Italy had formed a joint strategy "to impose significant and severe harm on the Russian economy" should Russia launch an invasion.
Biden is expected to speak to the four European leaders again after his talks with Putin.
Possible measures include restrictions on Russia's banks converting roubles into foreign currencies, or even disconnecting Russia from the Swift global financial payment system, reports say.
Before the talks, Bloomberg News reported that the US would seek to halt Russia's Nord Stream 2 pipeline to Germany.
Russia wants guarantees that Ukraine will not try to seize areas captured by Russian-backed separatists in 2014 and has warned the West not to cross "red lines" by adding Ukraine to Nato's military alliance.
More than 90,000 Russian troops are believed to be massed near Ukraine's borders.
A large part of the recent Russian military build-up is in Crimea, which Russia seized from Ukraine and then annexed in 2014.
Troops are also gathering near Ukraine's eastern Donbas region, the name for parts of Luhansk and Donetsk regions which are under the control of Russian-backed separatists.
Ukrainian officials have said Moscow could be planning a military offensive at the end of January.
More than 14,000 people have lost their lives in seven years of conflict since Russian-backed forces seized large areas of Ukraine's east.
- BBC