Sgt. Gary Stein will get an other-than-honorable discharge and lose most of his benefits for violating the policies, the Corps said.
The San Diego-area Marine who has served nine years in the Corps said he was disappointed by the decision. He argued that he was exercising his constitutional rights to free speech.
"I love the Marine Corps, I love my job. I wish it wouldn't have gone this way. I'm having a hard time seeing how 15 words on Facebook could have ruined my nine-year career," he told The Associated Press.
Gary Kreep, an attorney for Stein, said he would pursue administrative appeals within the Marine Corps but anticipates the effort will fail. He said he planned to file an amended complaint in federal court.
"As long as he wants to pursue this, we will be supporting him," said Kreep, who is executive director of the United States Justice Foundation, an advocacy group.
The Marines acted after saying Stein stated March 1 on a Facebook page used by Marine meteorologists, "Screw Obama and I will not follow all orders from him." Stein later clarified that statement, saying he would not follow unlawful orders.
Brig. Gen. Daniel Yoo, the commanding general of the Marine Corps Recruit Depot San Diego, said in a brief statement Wednesday that evidence supported an administrative board's recommendation to discharge Stein.
Tom Umberg, a former Army colonel and military prosecutor, said Stein persisted even after being warned.
"The Marine Corps gave him the opportunity to think about his actions, yet Sgt. Stein continued to undermine the chain of command," said Umberg, who was not involved in Stein's case. "I think his purpose was to leave the Marine Corps in a dramatic fashion in order to begin a career in talk radio or what have you."
Umberg believes the decision to discharge Stein will have limited impact because the vast majority of Marines would never consider such postings.
"I think 99 percent of the soldiers and Marines currently on duty understand the duties of supporting the chain of command and understand their rights of free speech are limited," he said. "To that 1 percent who don't know their rights to free speech are limited once they take the oath, this is a loud and clear message."
During a hearing, a military prosecutor submitted screen grabs of Stein's postings on one Facebook page he created called Armed Forces Tea Party, which the prosecutor said included the image of Obama on a "Jackass" movie poster. Stein also superimposed Obama's image on a poster for "The Incredibles" movie that he changed to "The Horribles," military prosecutor Capt. John Torresala said.
At the hearing this month at Camp Pendleton, Torresala argued that Stein's behavior repeatedly violated Pentagon policy and he should be dismissed after ignoring warnings from his superiors about his postings.
The military has had a policy since the Civil War limiting the free speech of service members, including criticism of the commander in chief.
Pentagon directives say military personnel in uniform cannot sponsor a political club; participate in any TV or radio program or group discussion that advocates for or against a political party, candidate or cause; or speak at any event promoting a political movement.
Commissioned officers also may not use contemptuous words against senior officials.
By ELLIOT SPAGAT
Associated Press