Top aides to President Joe Biden have been working on a proposal to create a sovereign wealth fund that would enable the United States to invest in national security interests, including technology, energy and key links in supply chains, according to a person familiar with the matter. The behind-the-scenes work of National Security Adviser Sullivan and his deputy, Dalip Singh, mirrors at least in part a proposal by Republican nominee Donald Trump on Thursday calling for a government-owned investment fund to fund "great national causes." Sullivan and Singh have been working on the project for months, conducting a weekly series of brainstorming sessions and meeting with economic experts on the National Security Council to discuss the size, structure, funding, leadership and potential protections for the proposed fund. Progress has been made and planning documents have been circulated among White House staff and key agencies, according to people familiar with the matter, but key details remain unclear.