SEOUL, South Korea (AP) — The rival Koreas dismantled huge loudspeakers used to blare Cold War-style propaganda across their tense border on Tuesday, as South Korea's president asked the United Nations to observe the North's planned closing of its nuclear test site.

The dismantling of dozens of loudspeakers was in line with an agreement on reconciliation by the leaders of the Koreas at their historic summit last Friday. It is still unclear if such measures can bring permanent peace because no major breakthrough in the North Korean nuclear standoff was produced at the summit.

South Korean soldi...