Justin Fulcher, a senior advisor to defence secretary Pete Hegseth has stepped down after six months of service at the Pentagon, the US department of defence (DoD) confirmed on Saturday.Fulcher announced his resignation publicly on Saturday afternoon in a post on X, writing: “As planned, I’ve completed 6 months of service in government to my country.” He described the experience as “incredibly inspiring.”“None of this could have happened without Secretary Hegseth’s decisive leadership or President Trump’s continued confidence in our team,” he wrote. “I will continue to champion American warfighters in all future endeavors.”Fulcher has been serving as a top aide to Hegseth since April. He had officially resigned on Thursday evening describing the decision as entirely his own and said it was always his plan to serve for six months in government, as reported by Fox News.He had initially planned to serve six months in government and upon completing that period, decided to step down on good terms. Fulcher also highlighted the important work being carried out by Hegseth in support of the military and the nation.In a statement, Pentagon spokesman Sean Parnell said, “The Department of Defense is grateful to Justin Fulcher for his work on behalf of President [Donald] Trump and Secretary Hegseth. We wish him well in his future endeavors.”During his tenure at the Pentagon, Fulcher advised Secretary Hegseth on personnel and policy matters. He was also involved in several key defence initiatives. He had helped in reviewing major acquisition programs focused on increasing military strength and improving the US defence industrial base. Fulcher also worked to speed up software procurement, reducing timelines from years to months and helped modernise important IT systems across the department.He accompanied Hegseth to high-level defence meetings in the Indo-Pacific region, including the Shangri-La Dialogue in Singapore. Fulcher also contributed to budget decisions that shifted nearly $50 billion from non-combat areas to programs that improve military readiness and effectiveness.He praised the dedication of DoD personnel and further cited progress in “revitalizing the warrior ethos” and “rebuilding the military”. Fulcher joined the DoD earlier this year as part of Hegseth’s inner circle, a group of loyal advisers appointed after Hegseth took charge of the Pentagon during Trump’s second term.His resignation comes amid a broader reshuffling of staff within Hegseth’s office. At least six aides have left since January, though defense officials say these are routine changes.The Pentagon has not yet announced who will replace Fulcher and his next role remains unclear. However, his statements suggest he plans to remain active in national security matters.