US National Security Advisor Jake Sullivan says that the US "could see circumstances in which a collective response by the alliance (NATO) to a cyber attack would be called by an ally." At a White House media briefing without Press Secretary Jen Psaki, who tested positive for Covid-19, Sullivan adds that Biden will discuss China's potential participation in the Ukraine conflict with allies during his trip to Europe. [COMPLETES VIDI326P3T3_EN & VIDI326P3GC_EN] IMAGES AND SOUNDBITES