The White House notified the Kremlin of Joe Biden’s intention to visit Kyiv hours before he departed for Ukraine, it has been revealed, as the details began to emerge of how the US president pulled off his high-profile diplomatic coup. Meticulously planned over several months by a tight circle of key advisers, Biden’s visit was described as “unprecedented in modern times” by his national security adviser, Jake Sullivan, on the grounds that it was the first time a US president had visited “the capital of the country at war where the United States military does not control the critical infrastructure”. “We did notify the Russians that President Biden will be travelling to Kyiv,” Sullivan said. “We did so 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, but I can confirm that we provided that notice.” The US informed Moscow to avoid any misunderstanding or misjudgment between the two nuclear-armed powers, according to accounts from Washington. Biden crossed into Ukraine at about 10pm on Sunday night, having quietly boarded a train in the Polish town of Przemyśl. His motorcade pulled up alongside his carriage allowing him to board unseen. His security detail took up most of the train’s eight carriages. According to a pool reporter on board, the journey through the night was uneventful with a few stops, at least one of which was to take on additional security guards. The train arrived at Kyiv-Pasazhyrskyi station at 8am on Monday. Biden took the final decision to go on Friday after huddling with his top aides in the Oval Office. Much of the trip until the final train ride had been shrouded in subterfuge. The journalist and photographer accompanying the president were sworn to secrecy and notified of the rendezvous arrangements under the title: “Arrival instructions for the golf tourney.” Prior to departure they had to hand over their phones, which were not returned until arrival in Kyiv. Eschewing the presidential Air Force One jet, Biden boarded an Air Force C-32, a modified Boeing 757 normally used for domestic trips to smaller airports with the call sign SAM060, for Special Air Mission. Prior to departure, the plane sat in a dark corner of Andrews airbase with its shades down, and it took off shortly after 4am on Sunday morning. Refuelling at Ramstein in Germany, Biden’s plane turned off its transponder for the roughly hour-long flight to Rzeszów, Poland, an airport that has served as the gateway for billions of dollars in western arms and VIP visitors into Ukraine. From Rzeszów, the president and his entourage were taken by motorcade on the hour’s drive to the train station at Przemyśl. Other foreign leaders who have come to Ukraine, including the former British prime minister Boris Johnson and the French president, Emmanuel Macron, have also come in by train from Poland – a route used by journalists, aid workers and diplomats, with Ukraine’s civilian airspace closed for the past year. Biden was met by the US ambassador to Kyiv, Bridget Brink, and taken in a convoy of vehicles which sped through closed-off roads to his meeting with Zelenskiy, using armoured vehicles that appeared to have been brought in discreetly in advance. US presidents visiting war zones is not unheard of: three visited Iraq, including Biden’s predecessor, Donald Trump, in what were seen at the time as major security operations. Barack Obama, Trump and George W Bush also visited Afghanistan. But compared with Kabul and the US Bagram airbase, which hosted visits, Ukraine was viewed as a very different proposition. That, White House officials are saying, is the distinction between this trip and previous presidential visits to Afghanistan and Iraq. In those countries, there was a massive US military presence, but there is none in Ukraine, and a minimal diplomatic presence. The active war zone is surveilled by Moscow’s electronic warfare aircraft, with Ukrainian society penetrated by Russian agents. The risks were apparent from the outset and planned for over “a period of months” by a handful of Biden’s closest aides with input from the NSC, the White House’s military office, the Pentagon, state department, and the intelligence community. After Moscow was informed of Biden’s trip, a Russian MiG 30 flew from Belarus, triggering an air raid alarm across Ukraine. If that flight was deliberate, it backfired, with the sirens audible during Biden’s visit serving only to underline his resolve. Describing the visit, Sullivan added: “That required a security operational logistical effort from professionals across the US government to take what was an inherently risky undertaking and make it a manageable level of risk.” “But of course, there was still risk and is still risk in an endeavour like this, and President Biden felt that it was important to make this trip because of the critical juncture that we find ourselves at as we approach the one-year anniversary of Russia’s full-scale invasion of Ukraine.” The go-ahead for the trip was given only on Friday, according to White House officials, after receipt of a final security briefing. Such was the level of secrecy that the handful of US pool reporters had their mobile devices taken from them before departure. Western surface-to-air missile systems have bolstered Ukraine’s defences, but the visit was a rare occasion when a US president has travelled to a conflict zone where the US or its allies did not have control over the airspace. In the end, however, Biden was insistent that he should visit the Ukrainian capital, which became a symbol of resistance to the invasion during the battle of Kyiv in the early weeks of the war, when Russia tried to take the city. “He got a full presentation of a very good and very effective operational security plan. He heard that presentation, he was satisfied that the risk was manageable and he ultimately made a determination [to travel to Kyiv],” said Sullivan. “This was risk that Joe Biden wanted to take,” added the White House communications director, Kate Bedingfield. “It’s important to him to show up, even when it’s hard, and he directed his team to make it happen no matter how challenging the logistics.” While Biden was in Kyiv, the state department announced a further $460m in US aid to Ukraine, including $450m worth of artillery ammunition, anti-armour systems and air defence radars, and $10m for energy infrastructure. The European Union’s foreign policy chief, Josep Borrell, said the bloc would approve more sanctions before the one-year anniversary of the conflict. After leaving Ukraine, Biden landed in the Polish capital Warsaw on Monday evening. On Tuesday he is set to deliver a speech to mark the anniversary of Russia’s invasion of Ukraine. He is also scheduled to meet President Andrzej Duda, along with other leaders of countries on Nato’s eastern flank.