WASHINGTON—A conflict within the Trump administration has come to light over how to implement the president’s new executive order that protects American investors from “malign” Chinese companies. Financial Times reported on Dec. 17 that the Treasury Department has attempted to “water down” the executive order that bans investment in companies with ties to China’s People’s Liberation Army (PLA). The Pentagon and the State Department, according to the report, have furiously opposed Treasury Secretary Steven Mnuchin’s effort to soften the ban. Mnuchin responded to media reports that exposed the interagency fight. “There is no disagreement between @SecPompeo and me regarding the implementation of the President’s Executive Order. We are coordinating closely on an interagency basis,” Mnuchin wrote Dec. 18 on Twitter. A few minutes after Mnuchin’s tweet, State Secretary Mike Pompeo, a China hawk, also denied the reports that alleged a clash between him and the Treasury secretary. “We are simply working to …