Russian President Vladimir Putin and US President Joe Biden spoke telephonically over the weekend about Russia’s military build-up, but the one-hour call ended without a breakthrough. Instead, Al Jazeera reports, the White House has insisted that Moscow faces “swift and severe costs” if it pushes ahead with aggression, while the Kremlin has denounced the United States’s “peak hysteria” surrounding the Ukraine conflict. Russia on Saturday added to the ominous tone by pulling some of its diplomatic staff out of Ukraine. The foreign ministry in Moscow said though that its decision was prompted by fears of “possible provocations from the Kyiv regime”.