By Bernadette Tuazon, Sarah Tilotta and Rebecca Wright, CNN

US President Joe Biden made a surprise visit to Kyiv, Ukraine, on Monday for the first time since Russia invaded Ukraine almost a year ago.

While in Kyiv, Biden announced a half-billion dollars in new assistance, including more military equipment, and he said new sanctions would be imposed on Moscow later in the week.

Here are some other times in history that a US president has visited a war zone.

President Franklin D. Roosevelt and US Gen. Dwight D. Eisenhower share a Jeep while visiting Castelvetrano, Italy, during World War II in December 1943. Gen. George S. Patton is standing on the left.
President Franklin D. Roosevelt and US Gen. Dwight D. Eisenhower share a Jeep while visiting Castelvetrano, Italy, during World War II in December 1943. Gen. George S. Patton is standing on the left.
Corbis/Getty Images
Eisenhower, as president-elect, eats with American soldiers on the front lines of the Korean War in December 1952.
Eisenhower, as president-elect, eats with American soldiers on the front lines of the Korean War in December 1952.
Bettmann Archive/Getty Images
President Lyndon B. Johnson shakes hands with American troops while visiting Vietnam in 1966.
President Lyndon B. Johnson shakes hands with American troops while visiting Vietnam in 1966.
Pictures From History/Universal Images Group/Getty Images
Johnson addresses American troops in South Vietnam in December 1967 and assures them that they have the support of their country.
Johnson addresses American troops in South Vietnam in December 1967 and assures them that they have the support of their country.
Bettmann Archive/Getty Images
President Richard Nixon greets troops in South Vietnam in July 1969.
President Richard Nixon greets troops in South Vietnam in July 1969.
David Turnley/Corbis/Getty Images
In January 1996, US troops salute President Bill Clinton in Bosnia and Herzegovina. US forces were there as part of peacekeeping efforts in the former Yugoslavia.
In January 1996, US troops salute President Bill Clinton in Bosnia and Herzegovina. US forces were there as part of peacekeeping efforts in the former Yugoslavia.
Diana Walker/Getty Images
President George W. Bush holds a Thanksgiving turkey while visiting US troops stationed in Baghdad, Iraq, in November 2003. The Iraq War began in March of that year.
President George W. Bush holds a Thanksgiving turkey while visiting US troops stationed in Baghdad, Iraq, in November 2003. The Iraq War began in March of that year.
Tim Sloan/AFP/Getty Images
Bush and first lady Laura Bush exit Air Force One as they arrive at an air base north of Kabul, Afghanistan, in March 2006.
Bush and first lady Laura Bush exit Air Force One as they arrive at an air base north of Kabul, Afghanistan, in March 2006.
Mandel Ngan/AFP/Getty Images
Bush, second from right, attends a teleconference with members of the US and Iraqi cabinets while visiting Baghdad in June 2006. Bush had made a surprise visit to meet with Iraqi Prime Minister Nouri al-Maliki.
Bush, second from right, attends a teleconference with members of the US and Iraqi cabinets while visiting Baghdad in June 2006. Bush had made a surprise visit to meet with Iraqi Prime Minister Nouri al-Maliki.
Jacob Silberberg/Pool/Getty Images
Bush greets troops while visiting an air base in Iraq's Anbar province in September 2007.
Bush greets troops while visiting an air base in Iraq's Anbar province in September 2007.
Jim Watson/AFP/Getty Images
Bush speaks with US troops in Baghdad in December 2008.
Bush speaks with US troops in Baghdad in December 2008.
Evan Vucci/AP
President Barack Obama speaks to military personnel while visiting Baghdad in April 2009.
President Barack Obama speaks to military personnel while visiting Baghdad in April 2009.
Charles Dharapak/AP
Obama meets with troops at the Bagram Air Base in Afghanistan in December 2010.
Obama meets with troops at the Bagram Air Base in Afghanistan in December 2010.
Jim Young/Reuters
Obama shakes hands with US Sgt. Chase Haag while visiting wounded troops in Afghanistan in May 2012. He presented Haag with a Purple Heart.
Obama shakes hands with US Sgt. Chase Haag while visiting wounded troops in Afghanistan in May 2012. He presented Haag with a Purple Heart.
Pete Souza/The White House/Getty Images
Obama greets US troops during a surprise visit to Afghanistan in May 2014.
Obama greets US troops during a surprise visit to Afghanistan in May 2014.
Saul Loeb/AFP/Getty Images
President Donald Trump and first lady Melania Trump greet members of the military as they arrive for a hangar rally at Al Asad Air Base in Iraq in December 2018.
President Donald Trump and first lady Melania Trump greet members of the military as they arrive for a hangar rally at Al Asad Air Base in Iraq in December 2018.
Andrew Harnik/AP
Trump serves food to US troops during a surprise visit to Afghanistan in November 2019.
Trump serves food to US troops during a surprise visit to Afghanistan in November 2019.
Tom Brenner/Reuters