SEOUL, South Korea >> South Korea sent rail cars and dozens of officials to North Korea today for joint surveys on northern railway sections the countries hope someday to connect with the South.

The weeks-long inspections, which will see South Korean cars running on North Korean tracks for the first time in a decade, represent one of the more significant goodwill gestures between the Koreas in past months as they move to reduce tensions across their heavily armed border.

Also today, the North and South Korean militaries were planning to finish destroying 20 front-line guard posts and removing land mines from a border area where they plan to start their first-ever joint search for remains of soldiers killed during the 1950-53 Korean War.

The Koreas plan to hold a groundbreaking ceremony by the end of the year on an ambitious project to connect their railways and roads agreed by their leaders. But beyond surveys and tape-cuttings, the Koreas cannot move much further along without the removal of U.S.-led sanctions against the North, which isn’t likely to come before it takes firmer steps toward relinquishing its nuclear weapons and missiles.

“Through the railways that will be connected in one, the South and North will prosper together and peace in the Korean Peninsula will become firmer,” South Korean Unification Minister Cho Myoung-gyon said during a ceremony at Dorasan Station near the border. “We will maintain close consultation with related nations so that the project to connect the South and North’s railways could proceed with international support.”

After whistling twice, a South Korean train engine pulling six rail cars slowly departed toward North Korea’s Panmun Station, near the town of Kaesong, where the rail cars will be reconnected to a North Korean engine.

According to plans outlined by Cho’s ministry, Korean officials will begin by surveying a 400-kilometer (248-mile) railroad section between Kaesong and Sinuiju that cuts through the North’s central region and northeastern coast. From Dec. 8 to 17, the Koreas will inspect an 800-kilometer (497 mile) railway section along the country’s eastern coast, stretching from an area near the scenic Diamond Mountain to a riverside station near the North’s border with Russia.

During the surveys, a North Korean train engine will pull six South Korean rail cars — including passenger and sleeping cars, a power-generator car and a fuel tanker — along the North Korean tracks to test operability.

The Unification Ministry said the North will attach its own rail cars to the vehicles, but it was unclear how many. Fifty-six South Korean officials will participate in the surveys, 28 each for the inspections on the western and eastern sections, the ministry said.

The Koreas in December 2007 began freight services between South Korea’s Munsan Station in Paju and the North’s Panmun Station to support operations at a now-shuttered joint factory park in Kaesong. The South used the trains to move construction materials north, while clothing and shoes made at the factory park were sent south. The line was cut in November 2008 due to political tensions over North Korea’s nuclear program and the hard-line policies of a new conservative government in Seoul.

The Kaesong factory park was shut down under the South’s previous conservative government in February 2016 following a North Korean nuclear test and long-range rocket launch.

The joint railway surveys were on hold before the U.N. Security Council on Saturday granted an exemption to sanctions that allowed them to proceed. Seoul initially said the joint surveys wouldn’t violate U.N. sanctions but later admitted Washington had different views and the two sides discussed the matter.

The plan to modernize North Korea’s outdated railways and roads and connect them with the South was among many agreements reached between North Korean leader Kim Jong Un and South Korean President Moon Jae-in, who met three times this year amid a diplomatic push that eased tensions over the North’s nuclear program. Kim also met with President Donald Trump in Singapore in June, when they issued a vague aspirational statement about a nuclear-free Korean Peninsula without describing how or when it would occur.

The follow-up talks have been rocky with North Korea insisting that sanctions should be removed first before any progress in nuclear negotiations. There’s also unease between the United States and South Korea over the pace of inter-Korean engagement, which Washington says should move in tandem with U.S.-led efforts to denuclearize the North.

Even if the North takes concrete steps toward denuclearization and gains sanctions relief, some experts say updating North Korean rail networks and trains, which creak slowly along the rails that were first built in the early 20th century, could take decades and massive investment.

At the most recent summit between Moon and Kim in September, the two leaders committed to reviving economic cooperation when possible, voicing optimism that international sanctions could end and allow such activity. They also announced measures to reduce conventional military threats, such as creating buffer zones along their land and sea boundaries and a no-fly zone above the border, removing guard posts and demining sections in border areas.