The consultations come as the Biden administration races to prevent what officials say could be an imminent Russian assault against Ukraine, which Moscow says is threatening Russian security by accumulating foreign weaponry and seeking to join the Western NATO military alliance.

But questions remained as Blinken conferred with European counterparts about how closely NATO nations are aligned on certain aspects of the Ukraine crisis, including how best to respond if Russia, which annexed Ukraine’s Crimea region in 2014, launches a renewed invasion.