South Korea and the United States on Thursday reaffirmed their commitment to defending "the hard-fought peace" on the divided peninsula as the allies marked the 70th anniversary of the outbreak of the Korean War.
Communist North Korea invaded the US-backed South on June 25, 1950, triggering a three-year war that killed millions.
The fighting ended with an armistice that was never replaced by a peace treaty, leaving the peninsula divided by the Demilitarized Zone and the two Koreas still technically at war.
"On this day in 1950, the US-ROK military alliance was born of necessity and forged in blood," US Secretary of Defence Mark Esper and his South Korean counterpart Jeong Kyeong-doo said in a joint statement.
The two paid tribute to the "sacrifice, bravery, and legacy of those who laid down their lives in defence of a free, democratic, and prosperous" South, the statement read.
Seoul's defence ministry puts the conflict's military fatalities at 520,000 North Koreans, 137,000 Southern troops and 37,000 Americans.
Seoul's relationship with Washington has been strained in recent years by the Trump administration's demands that it pay more towards the cost of keeping 28,500 US troops on the peninsula to protect the South from its nuclear-armed neighbour.
But the allies "remain firmly committed to defending the hard-fought peace on the Korean Peninsula," the statement added.
The anniversary comes as inter-Korean ties remain in a deep freeze following a rapid rapprochement in 2018 that brought three summits between North Korean leader Kim Jong Un and the South's President Moon Jae-in.
Kim on Wednesday suspended plans for military moves aimed at the South, after the North raised tensions last week by demolishing a liaison office on its side of the border that symbolised inter-Korean cooperation.
Recent events showed that inter-Korean relations "can turn into a house of cards at any time", the South's JoongAng Daily said in an editorial Thursday on the anniversary.
The South Korean government has "persistently turned a blind eye" to Pyongyang's provocations, it said, resulting in a "slackening sense of security".
"There is no free ride in keeping peace," the editorial read, adding: "We hope the government and defence ministry deeply reflect on the lesson of 70 years ago."
A young girl with her brother on her back walks past a stalled M-26 tank at Haengju, Korea in June 1951
Factfile on the 1950-1953 Korean War
South Korean soldiers walk past the former North Korean Workers Party headquarters in Cheorwon
South Korean honour guards carry portraits and urns of compatriot soldiers killed during the 1950-53 Korean War, during a burial ceremony at the National Cemetery in Daejeon