U.S. President Joe Biden did little to tip his hand about his unannounced visit to Kyiv, heading to church on Saturday afternoon and then taking his wife out to dinner at a cozy Washington restaurant.

But by the pre-dawn hours Sunday, he was already aboard a U.S. military plane crossing the Atlantic, the first leg of an itinerary to the Ukrainian capital carried out under cloak-and-dagger secrecy after months of meticulous planning by a close circle of advisers.

Americans woke up on a public holiday, Presidents’ Day, to clips of Biden in his trademark aviator sunglasses strolling in the cold next to Ukrainian President Volodymyr Zelenskyy as air raid sirens blared in the background.