SEOUL, South Korea — North Korea has started dismantling a missile-engine test site, as President Trump said the North’s leader, Kim Jong-un, promised he would during their historic summit meeting in Singapore in June, according to an analysis of satellite imagery of the location.

The North Koreans have started taking apart the engine test stand at the Sohae Satellite Launching Station, said Joseph S. Bermudez Jr., an expert on North Korea’s weapons programs, in a report published on Monday on the website 38 North. The dismantling work probably began sometime within the last two weeks, he said.

North Korea has also started dismantling a rail-mounted building at the Sohae station where workers used to assemble space launch vehicles before moving them to the launchpad, Mr. Bermudez said.

Mr. Bermudez compared satellite photos of the Sohae facilities taken on Friday and Sunday to conclude that North Korea had begun taking “an important first step toward fulfilling a commitment made by Kim Jong-un.”