The U.S. State Department on Tuesday marked the 69th anniversary of the outbreak of the Korean War, calling it history that should not be forgotten.

Department spokesperson Morgan Ortagus wrote on her official Twitter account that "the Korean War anniversary is a reminder of allied troops' selfless bravery and U.S. and South Korea resolve to defend liberty against aggression in the past and future." 

She said this history should be taught in the Indo-Pacific region and around the world -- not forgotten or distorted.

The U.S. fought alongside South Korea under the United Nations flag against an invasion by North Korea, which was later supported by Chinese forces. 

The South Korean Embassy in the U.S. on Tuesday held a memorial ceremony at the Korean War Veterans Memorial in Washington, with veterans and U.S. officials in attendance to pay tribute to those who gave their lives defending freedom in the South.