U.S. President Joe Biden's surprise visit to Ukraine on Monday took weeks of preparation and careful planning.
U.S. officials say Biden took unusual steps – such as not flying aboard his official Air Force One plane – to arrive safely for a one-day visit to Ukraine's capital, Kyiv.
It was the first time in modern history that an American leader had traveled to an active conflict area without receiving protection from the U.S. military, The Associated Press reported.
White House officials admitted that such a trip carried possible risks, even though Russia was informed ahead of time about Biden's visit.
Biden left the White House around 3:30 a.m. Sunday.
He flew to Europe aboard an Air Force C-32, a plane commonly used for transporting military passengers.
During a refueling stop in Germany, the president stayed aboard the plane as it prepared for a one-hour flight to Rzeszow, Poland.
From there, Biden got on a train for a 10-hour overnight trip to Kyiv, the AP reported.
The trip was not announced to the Ukrainian public.
When Biden arrived, he made several stops around the capital Kyiv.
He was transported in a white-colored vehicle instead of his usual, armored presidential car.
For months, Biden had considered joining the list of other Western officials who have visited Kyiv to show support for the country as it battles Russian forces.
Russia invaded Ukraine about one year ago.
Biden had already planned to visit Warsaw, Poland.
Officials decided the Presidents' Day holiday would be a good chance for him to stop over in Kyiv, the AP reported.
Top officials at the White House and U.S. national security agencies began working in secret for months to make the trip happen, national security adviser Jake Sullivan said Monday.
Biden gave final approval to the plan last Friday.
Sullivan said the trip required assistance from many agencies to deal with security, operations and transportation.
That goal, Sullivan said, was to attempt to turn "an inherently risky" trip into something manageable.
Biden met with Bridget Brink, the U.S. ambassador to Ukraine.
He then entered his car for the drive to the city's Mariinsky Palace, the official home of Ukrainian president Volodymyr Zelenskyy.
Biden also met with and visited parts of Kyiv with Zelenskyy.
Even while he was on the ground in Ukraine, flights transporting military equipment and other goods continued to Poland from Western cities.
Across Kyiv, many main streets and central areas were blocked off without explanation.
People started sharing videos of long lines of official vehicles traveling quickly through city streets.
Biden traveled with a far smaller group of advisors than usual.
They included Sullivan, deputy chief of staff Jen O'Malley Dillon and the director of Oval Office operations, Annie Tomasini.
They were joined by his Secret Service protectors, a small medical team and an official White House photographer.
Also traveling with Biden was a military aide who carries the so-called "nuclear football."
The nuclear football is a name used for a special bag that contains needed information for the president to order the use of nuclear weapons in case of a national emergency.
Only two reporters traveled in the group instead of the usual 13.
A small number of Ukraine-based media representatives were called to a downtown hotel and informed of Biden's arrival.
It was rare for a U.S. leader to travel to a combat area where the U.S. or its allies do not have control over the airspace.
The U.S. military does not have a presence in Ukraine other than a small amount of Marines guarding the American embassy in Kyiv.
I'm Bryan Lynn.