USA! USA!

Elena is a Russian citizen, and will retain that Russian citizenship for life, unless she formally renounces it.

She's also, now, a naturalized US citizen.  The way this works is IF:
(a) a child is under 18,
(b) she's legally adopted by a US citizen, and
(c) all the paperwork is completed so she can legally emigrate to the United States as a permanent resident alien (on a green card, in other words)

THEN she's automatically a US citizen the minute the plane touches down on US soil.

That means Elena had to travel between Moscow and Washington DC an a Russian passport as a Russian citizen, but now she's got dual citizenship.

We actually sort of marked the moment she gained US citizenship.  This was the end of a pretty long flight, and Elena was getting more than a bit fussy.  However, the end of the flight has all sorts of bumps and dips and noises as the plane approaches the runway, and Elena likes the novelty, so she was paying attention.

As we were just about to touch down, I started psyching her up with "ready? ready? ready?..." and then kaBUMP! we landed, I said "NOW!", the pilot started decelerating, and at the same time the hydraulic flap control lines started vibrating the roof of the cabin.

Elena liked the kaBUMP and the overhead hydraulic whine, so the second we touched down, her finger shot up to point at the roof and she went, "OOOOOOOooooooo!"

Welcome to America, kid.  You're a citizen now; it's your country, too.

Elena's Russian passport picture