South Korea's top negotiator in defense cost-sharing talks with the United States reaffirmed on Monday that costs should be shared in a "fair and reasonable" manner. 

Jeong Eun-bo, the top envoy to the Special Measures Agreement(SMA) negotiations, made the comment upon arriving at Washington's Dulles International Airport ahead of a fourth round of talks set for Tuesday and Wednesday.

Jeong said that the most important principle is that the negotiations must contribute to the South Korea-U.S. alliance and the strengthening of their joint defense posture.

He added Seoul's position is to negotiate within the current framework of the SMA, indicating it will not accept the U.S.' apparent demand that Seoul pay more in additional categories not specified in the agreement.

The current SMA requires Seoul pay for South Korean civilians hired by the U.S. Forces Korea, the construction of military facilities to maintain the allies' readiness and other forms of support.

The U.S. has reportedly demanded Seoul increase its contribution some 500 percent to nearly five billion dollars next year. Under such terms, Seoul would be responsible for costs such as the rotation of U.S. forces and off-peninsula drills. 

The previous round of SMA talks in Seoul last month was cut short, displaying publicly a rift between the allies over how to share the costs for the stationing of American troops in South Korea.