The alliance was forged in the 1950-53 Korean War and some 28,000 U.S. troops remain in South Korea, to the fury of North Korea, which defends its development of nuclear weapons citing the danger of what it says is a U.S.-South Korea plan to invade.

While no South Korean government has ever seriously questioned the alliance, and public support is solid if not overwhelming, former U.S. President Donald Trump caused consternation with a suggestion that U.S. forces could pull out.

The conservative President Yoon Suk Yeol hailed the importance of the alliance on a visit to the White House this year, where he sang the hit "American Pie" for President Joe Biden.

The government's information campaign for the anniversary features a video, broadcast on social media and in cinemas, that includes a clip of that sing-song, along with images of the two countries' flags and the rap song.

"A perfect chemistry protecting freedom and solidarity, mutually advantageous for industry and the economy," go some of the lyrics.

The information campaign is intended to "heighten the public's understanding of the South Korea-US alliance", the culture ministry told Reuters.

The South Korean embassy in the United States staged a fashion show last month marking the anniversary, with models in traditional Korean dresses featuring South Korean and U.S. flags.

SOFT POWER

South Korea's showcasing of its U.S. ties comes after rival North Korea has been making much of its relations with its old partner, Russia.

Russia's foreign and defence ministers have both visited North Korea in recent months and its leader, Kim Jong Il, met Russian President Vladimir Putin in September in Russia.

South Korea's spy agency suspects that North Korea has sent Russia more than 10 shipments of munitions for its war against Ukraine, a politician briefed by the agency said on Wednesday.

U.S. forces, meanwhile, have held a series of military exercises in the region including one last month with South Korea and Japanese forces featuring a U.S. B-52 strategic bomber.

Lee Gyu-tag, an associate professor of global affairs at George Mason University Korea, said South Korea was trying to tap into pop culture to bolster support for the alliance but it risked a backlash.

"When soft power is so blatantly used for a purpose, people won't like it and it might even backfire," Lee said.

While some online commentators praised the rap video others said it was "cringey".

Overall, about one in two South Koreans believe the alliance should be strengthened, according to a Gallup Korea poll commissioned by the government in September.

The U.S. Embassy is marking the friendship with a limited edition "Alliance Pale Ale" at its cafeteria in Seoul, made by a South Korean brewery with ingredients from both countries, in cans featuring Korean tigers and U.S. eagles.

(Reporting by Hyunsu Yim; editing by Robert Birsel)

By Hyunsu Yim