WASHINGTON: US President Joe Biden on Saturday discussed the unfolding crisis in Russia with the leaders of France, Germany and the United Kingdom, affirming the allies’s staunch support for Ukraine.

According to a statement from the White House, Biden spoke by telephone with French President Emmanuel Macron, German Chancellor Olaf Scholz and UK Prime Minister Rishi Sunak about “the situation in Russia.”

In Moscow, President Vladimir Putin is facing the biggest threat to his rule yet with rebel mercenaries advancing towards the Russian capital after seizing a key military base.

The leaders “affirmed their unwavering support for Ukraine,” the White House statement added.

A White House spokesman also said Biden and Vice President Kamala Harris were briefed by their national security team Saturday morning on the Russian crisis and will continue to be briefed throughout the day.