Because the head of CDC believes THIS: "Were not going to hermetically seal the borders of the US. Were reliant and interdependent with the world for travel, for trade, for the economy, for our families and communities."
Because the head of CDC believes THIS: “Were not going to hermetically seal the borders of the US. Were reliant and interdependent with the world for travel, for trade, for the economy, for our families and communities.”
Or, becaue the CDC lacks jurisdiction over which flights can land in London.