The top U.S. diplomat and defense chief have jointly called on South Korea to shoulder more of the upkeep costs for stationing American troops on the Korean Peninsula.

In a rare joint commentary in the Wall Street Journal on Thursday, U.S. Secretary of State Mike Pompeo and Defense Secretary Mark Esper described South Korea as a "global economic powerhouse" that can and should contribute more to its defense.

The secretaries said that Seoul bears no more than one-third of the costs most directly associated with U.S. Forces Korea and that U.S. contributions to South Korea's defense far exceed the cost of U.S. "boots on the ground."

Calling the South Korea-U.S. alliance the "linchpin" of peace and prosperity in Northeast Asia, Pompeo and Esper claimed the longstanding U.S. commitment and presence have enabled South Korea's vibrant democracy and its economy to become the world's 12th-largest.

The secretaries then claimed more than 90 percent of South Korea's cost-sharing contributions go back into the local economy in the forms of salaries for South Korean employees of U.S. Forces Korea, construction contracts and other services.

Washington is apparently ramping up pressure on Seoul to increase what it pays for defense after six rounds of bilateral cost-sharing negotiations have failed to create a breakthrough.

The U.S. has reportedly demanded a fivefold increase from around 870 million dollars last year to five billion dollars. Seoul, meanwhile, argues its share should be decided within the framework of the Special Measures Agreement.