Washington (CNN) In his first post-Trump administration interview, former White House counterterrorism adviser Sebastian Gorka said former chief strategist Steve Bannon and others in their camp have been "systematically undermined" in the White House.

Gorka also stressed to Breitbart's Matt Boyle on SiriusXM Patriot on Saturday morning that he decided to resign after President Donald Trump delivered a speech Monday night outlining the US path forward in Afghanistan, including an unspecified troop increase.

"I realized after the President's speech this week on Afghanistan that he's not being well-served," Gorka said. "That speech was written by people for the President in direct contravention of everything that we voted for November the 8th."

Gorka's exit -- which several White House officials told CNN was a dismissal rather than a resignation -- was just the latest in a series of high-profile White House departures in recent months. Bannon, who was widely considered to be the driving force behind Trump's nationalist and hardline immigration stances, was fired last week.

Gorka's departure comes about a month after retired Gen. John Kelly took over as chief of staff , looking to instill order in a chaotic White House beset by internal divisions, staff infighting and a storm of controversies.

It also comes as the White House seeks to reset the media narrative after Trump's widely panned response to the racially motivated violence in Charlottesville, Virginia, earlier this month.

Gorka is a former national security editor at the conservative news site Breitbart. Bannon, who has since returned to the site as its executive chairman, once described Breitbart as a " platform " for the so-called alt-right -- a loose association of far-right groups that generally believe in such things as isolationism, protectionism and white nationalism.

Gorka was a vocal advocate for Trump throughout his time in the White House, and in the interview touched on various issues he said had been wins for the administration, such as stepping up efforts to destroy ISIS, increasing support for Israel and deterring illegal immigration.

"On key issues, we've done great things, but unfortunately, those who don't believe in many of those things are now at the helm in key places and we have to make sure that they maintain the MAGA doctrine and we're going to be doing that right now," Gorka said.

Although Gorka could often be spotted on television touting Trump administration talking points, and was vocal about Islamist terrorism , he was not a member of the National Security Council and did not play a major policy-making role, according to administration officials. Bannon was removed from his permanent seat on the council in April, and several officials who came to the council under fired national security adviser Michael Flynn were also dismissed in recent weeks, including retired Col. Derek Harvey and the council's senior director of intelligence, Ezra Cohen-Watnick.

In his interview Saturday, Gorka said: "It is important now that key personalities inside the NSC have been removed that we keep the pressure on from the outside because we must continue until global jihadism is a laughing stock and does not pose a serious threat to America and our friends or allies"

Gorka echoed comments Bannon made after he left the administration regarding the officials who now occupy the West Wing.

Gorka said on Saturday: "I decided, just as with Steve, we can be far more effective for the President on the outside, and it's a very exciting day for me and my family to start again supporting the MAGA message as private citizens."