ITV News US correspondent Robert Moore reports on the Ukrainian president's secretive visit
It was one of the best kept secrets in Washington.
Indeed, the news was so tightly held that many senior officials didn't know there would be an end-of-year VIP coming straight from the battlefield to the White House.
President Zelenskyy's arrival this morning in the US capital is a calculated risk, but it makes sense in many different ways.
First of all, he has come to say thank you. By the end of this year - once the latest spending bill has passed Congress - the US will have given Ukraine a staggering $100 billion in military and financial aid.
Secondly, Zelenskyy can see a political problem that needs to be addressed with urgency. The Republicans take control of the House of Representatives next month.
Many are America-First nationalists - with an isolationist streak - and they are sceptical of spending billions of dollars on Ukraine protracted war.
So part of the Ukrainian mission today is to keep US support for Kyiv a cross-party, bipartisan affair. We can expect lots of powerful symbolism and much talk of keeping the flame of democracy burning bright in the face of Moscow's tyranny and aggression.
There is a third and transactional reason that Zelenskyy has come to Washington. He wants the world's best air defence system.
So far, the US has been reluctant to provide Patriot batteries, with their powerful radar and interceptor missiles.
The Pentagon has long feared it crosses a Russian red line and would be seen by the Kremlin as a major escalatory step.
President Biden has long tried to walk a strategic tightrope: provide massive levels of military support to Ukraine but not get drawn directly into the conflict.
But the calculus has recently shifted.
'He's come straight from the battlefield here to Washington with a very specific request'
It seems that the Zelenskyy visit means he can go back home with the ultimate Christmas present: a US promise to provide a whole new level of military technology, including those precious Patriots.
Ukraine remains in a battle for its survival. So even amid the deafening cheers and back-slapping we will see today on Capitol Hill - tonight Zelenskyy will be addressing a joint session of Congress - this is about much more than mutual appreciation.
It is about requesting and receiving American money and high-tech weaponry on a prodigious scale.
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