White House officials breathed a sigh of relief when Joe Biden's train safely left Ukraine on Monday evening.

Meanwhile, Ukrainian rail chiefs were able to celebrate the success of their biggest VIP mission so far. 

'It was an honor and a privilege for me and the whole #IronTeam of Ukrainian Railways to deal with this visit,' tweeted Alexander Kamyshin, the chief executive of Ukrainian Railways. 

'I must say, it was complicated. But we did it. That's how #RailForceOne appeared.'

He tweeted a string of pictures of Amtrak Joe riding the rails in Ukraine, along with a locomotive in Ukrainian colors, carrying the Stars and Stripes.

And he even offered a graphic showing how 'on-time departures' had been affected by the special mission along with a humble brag.

'I also want to apologize for breaking our OTP (On Time Performance) yesterday. We had to delay some of our trains to give a way to #RailForceOne.' he said.

'It was painful for me and my team, but I had to do that. So only 90% of our trains arrived on time yesterday. I apologize.'

The train from Przemysl Glowny in south-eastern Poland to Kyiv has seen its share of VIPs. It is the safest route for visitors to reach the Ukrainian capital. 

Biden and a stripped down team boarded the the train's VIP carriages at about 9:15pm local time on Sunday evening for the 10-hour journey.

American officials assumed their cover would have been blown by now, but they managed to slip secretly into Kyiv.

Kamyshin said he could not say too much more about how they managed the mission. But he reflected on the surreal business of ferrying an American president to Ukraine. 

'I don't actually remember how we got from Putin's idea to "take Kyiv in 3 days" to President #Biden walking across #Kyiv together with my President #Zelensky on the 362nd day of the war,' he wrote.

Ensuring the president's comfort was vital, he added. 

'Out of 24 hours, president Biden spent 20 on the train (both directions), and only 4 in Kyiv. That's why it was important for us to care about him in a proper way. And we did. 

It was all part of the war effort, he added. 

'I will not tell much more about this mission. Just believe me, it was quite a complicated project for us. Our #IronDiplomacy program helps my country withstand in this war, that's why we #KeepRunning'

The trip came after of weeks of meticulous planning that included a fake schedule for Monday morning, armored convoys and American warplanes in airspace along the Ukrainian border.

'Unlike previous visits from presidents to war zones, like Iraq and Afghanistan the U.S. obviously does not have a military presence on the ground in Ukraine, which made a visit from a sitting president all the more challenging,' White House Communications Director Kate Bedingfield told reporters. 'But this was a risk that Joe Biden wanted to take.' 

The trip began with an act of deception, to throw journalists off the scent. 

Every evening, the White House publishes President Joe Biden's public schedule for the following day.

On Sunday, it said he would receive his daily national security briefing on Monday morning as normal before leaving the White House at 6:40pm to travel to Poland.

But by the time the schedule dropped into reporters' inboxes just after 7pm on Sunday, Biden was long gone. He was already half way to the Ukrainian capital Kyiv.

For this trip, Biden traveled with a stripped down retinue. Only a handful of his closest advisers accompanied a small medical team and his Secret Service detail to Joint Base Andrews before dawn on Sunday morning. 

The traveling press pool was reduced from the normal 13 people to just two: A photographer and reporter. On Friday, they were briefed about the destination and sworn to secrecy.

They were told further instructions would come in an email with the subject line: 'Arrival instructions for the golf tourney.'

The only aides were Jake Sullivan, the president's national security adviser; Jen O’Malley Dillon, his deputy chief of staff; and Annie Tomasini, the director of Oval Office operations.

They boarded the plane — with shades drawn — when it was parked beside a hangar. On normal trips it would have been parked in plain sight out on the apron. The two journalists were asked to give up their phones.

Their transatlantic flight left at 4:15am, before daybreak. 

They traveled on one of the smaller presidential jets, based on a 757, which causes less of a stir wherever it arrives. And it carried the call sign 'SAM060,' for Special Air Mission, instead of Air Force One. 

After a refueling stop at the American base in Ramstein, Germany (where shades again remained down) its crew turned off the transponder for the one-hour hop to Rzeszów.

Rzeszów is the transport hub for incoming VIPs can catch an overnight train direct to Kyiv.

With the air space above Ukraine contested by Russian warplanes, the 10-hour train journey remains the safest route in.

Biden and his retinue boarded a convoy of SUVs and minivans for the one-hour trip Przemyśl Główny train station. 

Biden has been desperate to visit Kyiv for months. But his Secret Service protectors said there was no way they could safely get him in and out, even as French President Emmanuel Macron, German Chancellor Olaf Scholz, Canadian Prime Minister Justin Trudeau and two British prime ministers, Boris Johnson and Rishi Sunak, made the journey.

Other options had been reviewed such as a quick hop across the border (rather like the first lady did last year) to meet President Volodymyr Zelensky, or a longer trip to the western city of Lviv.

This time around, the final decision lay with Biden himself.

President Biden spoke for 10 minutes at the Mariinsky Palace in Kyiv on Monday morning. He expressed his continuing commitment to Ukraine's fight and announced fresh aid. 

These were the main points: 

'Democracy stands' 

'One year ago, the world was literally at the time bracing for the Fall of Kyiv ... Perhaps even the end of Ukraine

'One year later Kyiv stands. Ukraine stands. Democracy stands. 

'The Americans stand with you and the world stands with you.'

On aid 

'Today, that announcement includes artillery ammunition for HIMARs ... more Javelins, anti-armor, air surveillance radar to protect Ukrainian people. 

'Later this week we will announce additional sanctions against elites in companies that are trying to evade sanctions and back the Russian war machine borders. 

'And thanks to a bipartisan support in Congress, this week we're delivering billions in direct budgetary support, billions in direct support which the government can put to use immediately to help provide basic services to citizens.'

Putin is losing

'Russia's aim was to wipe Ukraine off the map. Putin's war of conquest is failing. Russia's military has lost half the territory it once occupied.

'Young talented Russians are fleeing in the tens of thousands, not wanting to come back to Russia. Not just fleeing from the military, fleeing from Russia itself because they see no future in their country.'

On Putin's miscalculation

'When Putin launched his invasion nearly one year ago, he thought Ukraine was weak and the West was divided. He thought he could outlast us. But he was dead wrong.

'As you know, Mr. President, I said at the beginning, he's counting on us not sticking together. He was counting on an inability to keep NATO United

He was counting on us not to be able to bring in others on the side of Ukraine. 

'He thought he could outlast us. I don't think he's thinking that right now. God knows what he's thinking.'

'The president was fully briefed on each stage of the plan and any potential contingencies and then made the final go or no-go decision after a huddle in the Oval Office, and by phone, with some key members of his national security cabinet on Friday,' said Deputy National Security Adviser Jonathan Finer.

Only a handful of the relevant officials were briefed on the planning to ensure secrecy.

And there was one further step to ensure that nothing could go wrong: warning the Russians to back off, in case they took any action that could pitch the U.S. and Russia into a direct war.

'We did notify the Russians that President Biden will be traveling to Kyiv,' said National Security Adviser Jake Sullivan. We did some hours before his departure for deconfliction purposes. 

'And because of the sensitive nature of those communications I won't get into how they responded, or what the precise nature of our message was.'

His train pulled out Przemyśl Główny at about 9:30pm local time.

Much of the journey was in the dark with little visible beyond streetlights and the shadows of buildings in the distance. 

The first the world knew of Biden's arrival was when photos emerged of him on a walkabout with President Volodymyr Zelensky in downtown Kyiv.

The White House had hoped they could keep the trip secret until the president was safely back in Poland. It wasn't to be. 

The traveling press pool had been barred from sending real-time updates on Biden's location. Instead, they sent updates only after he had arrived in Kyiv, and offered no details about the nature of his journey in.

Reports suggested that American warplanes had been unusually busy in the skies over Poland close to the border, although officials said they had not crossed into Ukrainian airspace. 

They included E-3 Sentry airborne radar and an electronic RC-135W Rivet Joint aircraft, both of which carry surveillance capabilities.

Details of Biden's visit were reported out about an hour after each happened. There was his arrival at the Mariinsky Palace, where was met by Zelensky and first lady Olena.

There they met to discuss how the U.S. can continue to support Ukraine. 

'I thought it was critical that there not be any doubt, none whatsoever, about US support for Ukraine in the war,' said Biden, explaining the reason for his visit, as he sat for talks.

From there it was on to St. Michael's Gold-Domed Cathedral and a chance to pay respects to Ukraine's war dead. The pair left wreathes at a memorial, undaunted by the sound of air raid sirens blaring around the city.

Then Biden met with U.S. embassy staff. 

By 2pm local time the press pool had been cleared to announce that Biden was no longer in Kyiv. In all, he had spent about five hours on the ground.

Delighted officials then briefed the media, using words such as 'historic' and 'unprecedented.'

Officials offered no further details about how he had got in or out. They said they would do so only once the trip was completed. 

Sullivan said Biden had been excited about the trip and had given the green light once hearing a full safety assessment. that the security risks were not not enough to prevent  

'I will just say that he got a full presentation of a very good and very effective operational security plan,' he said. 

'He heard that presentation. He was satisfied that the risk was manageable. And he ultimately made the determination.'