Here is more from Josh Rogin of The Washington Post:
The Strategic Initiatives Group grew out of [Stephen] Bannon's admiration for the Pentagon's Office of Net Assessment, the internal think tank that is meant to consider long-term, over the horizon strategic challenges, the official said. In a four-year presidential term, long-term may be only months, but the Strategic Initiatives Group is not designed to fight the day-to-day battles over issues in the news.
Some call the Strategic Initiatives Group Bannon's internal think tank. It's led by Christopher Liddell, a former General Motors executive who hails from New Zealand. Goldman Sachs executive Dina Powell is also heavily involved, along with Baltimore real estate developer Reed Cordish. On the national security side is Sebastian Gorka, a controversial pundit and analyst with strong views on how to fight the war against Islamist extremism.
Here is the previous Think Tank Watch post on the White House's internal think tank, which is also being referred to a the "shadow National Security Council."
The only person on the Strategic Initiatives Group (SIG) with previous think tank experience is Sebastian Gorka, who is known as Trump's "Jihad Whisperer."
Gorka worked at the RAND Corporation but left after less than one year to establish his own think tank, the Center for Euro-Atlantic Integration and Democracy.
Later, he and his wife established The Institute for Transitional Democracy and International Security (2003-2008). He was also one of the founding members of the Council on Emerging National Security Affairs (CENSA).
From 2009-2014 he was a Military Affairs Fellow for the National Security Fellowship Program at the Foundation for the Defense of Democracies (FDD), and a member of the Strategic Advisers Group at Atlantic Council from 2008-2010.
In 2014 he took a teaching job at Marine Corps University (part of the Defense Department), where his academic chair was funded by Thomas Saunders III, a major Republican Party donor and Chairman of the Heritage Foundation.
Gorka's wife, Katharine Gorka, is currently the President of the think tank Council on Global Security.