WASHINGTON—The Trump administration is moving ahead with plans to divert $3.6 billion from military-construction projects to build or fortify portions of a wall along the U.S.-Mexico border.

Defense Secretary Mark Esper called House Speaker Nancy Pelosi (D., Calif.) on Tuesday to detail the funding shifts, which would be divided about evenly between domestic and international military projects, the Pentagon said.

Mr. Esper authorized diverting funds for 11 wall projects, which would delay as many as 127 military projects, the Pentagon said.

Defense officials wouldn’t say which military projects would be affected until the Pentagon had notified all members of Congress whose districts would be affected, a process they said would be completed by Wednesday. Defense officials said that affected embassies also were being notified.

Pentagon officials said the military-construction projects had been deferred, not canceled, but Mr. Esper’s decision could amount to defunding the projects. Democrats have vowed to not re-appropriate money for the affected military projects.