Defense Secretary Melvin R. Laird said yesterday that the U.S. combat role in South Vietnam will end after the middle of next summer. An aide, however. explained. "We will always have American troops protecting the remaining forces."

Laird praised the "Vietnamization" program, telling a news conference the South Vietnames forces are "much better equipped, much better trained, and leadership has improved to the point where they are able to take over the military burden."

U.S. combat forces. Laird said, "which will be assigned to the logistics, support and artillery roles, will not be a combat mission, but will be a security mission. They will be there to protect and support the forces that are assigned these roles."

Laird's statement did not mean that U.S. soldiers will no longer be engaged in combat. although their role will be to protect logistics, air, and artillery bases. If the NLF attacks the bases. the aide explained, U.S. troops will be drawn into battle.

Laird gave no indication of when he thought the last American troops could all be out of Vietnam.

He said Phase One of the Vietnamization program, the training of troopsfor combat, would be completed this year. Phase Two, the training and equipping of South Vietnamese to take over logistics and support missiles, requires much more time than the first, he said.

American forces in South Vietnam will be cut from a ceiling figure of 549,500 in January 1969 to less than 284,000 May 1, Laird said. He did not give a timetable for further reductions.