NBC News veteran William Arkin penned a memo to colleagues Wednesday announcing his resignation over what he described as the “Trump circus” that is increasingly favored over real journalism.

Mr. Arkin, an Army veteran who has worked for NBC on and off for more than 30 years as a reporter and military analyst, announced in his memo, obtained by CNN, that Friday would be his last day at the network and that he was taking the time off to work on multiple books and other projects.

Mr. Arkin, who is staunchly anti-war and far from being a supporter of Mr. Trump, said part of his reason for leaving NBC was the network’s obsession with opposing the president at every turn.

“Of course he is an ignorant and incompetent impostor. And yet I’m alarmed at how quick NBC is to mechanically argue the contrary, to be in favor of policies that just spell more conflict and more war,” he wrote. “Really? We shouldn’t get out Syria? We shouldn’t go for the bold move of denuclearizing the Korean peninsula? Even on Russia, though we should be concerned about the brittleness of our democracy that it is so vulnerable to manipulation, do we really yearn for the Cold War? And don’t even get me started with the FBI: What? We now lionize this historically destructive institution?”

Mr. Arkin argued that NBC, and news outlets like it, often miss crucial news stories because they’re so caught up in the “day-to-day whirlwind and hostage status as prisoners of Donald Trump.”

He also lamented that the national security establishment gained “dangerous strength” under the Trump administration and that NBC “somehow” found itself defending “Washington and the system.”

“I’d also argue, ever so gingerly, that NBC has become somewhat lost in its own verve, proxies of boring moderation and conventional wisdom, defender of the government against Trump, cheerleader for open and subtle threat mongering, in love with procedure and protocol over all else (including results),” he wrote. “I accept that there’s a lot to report here, but I’m more worried about how much we are missing.”

The network had no comment on Mr. Arkin’s departure, CNN reported.