A TV presenter working for the Kremlin-funded broadcaster Russia Today (RT) has denounced as "wrong" Russia's "military intervention" in Ukraine.
"I can't stress enough how strongly I am against any state intervention in a sovereign nation's affairs," Abby Martin declared in her news programme.
RT said it respected Ms Martin's views, and that she would not be reprimanded.
Armed men dressed in what appear to be Russian uniforms have surrounded army bases in Ukraine's Crimea peninsula.
The southern region has become the major focus of post-uprising Ukraine, with Kiev accusing Moscow of invading Crimea.
But Russian President Vladimir Putin has denied the presence of his troops in the peninsula, saying those surrounding military bases were pro-Russian self-defence groups.
'Rife with disinformation'
Ms Martin made her remarks at the end of her Breaking the Set show, broadcast from a studio in Washington.
"Just because I work here doesn't mean I don't have editorial independence," she said, adding: "What Russia did was wrong."
The outspoken presenter admitted that she did not possess in-depth knowledge of Ukraine's history or "cultural dynamics", but insisted that military intervention was not the answer.
"I will not sit here and apologise for, or defend, military aggression," she said.
Ms Martin also criticised press coverage of the Ukrainian crisis, calling it "rife with disinformation" and "disappointing from all sides of the media spectrum".
In response to the journalist's on-air statement, the Russian TV channel said: "Contrary to the popular opinion, RT doesn't beat its journalists into submission, and they are free to express their own opinions, not just in private but on the air."
The broadcaster added that it would send Ms Martin to Crimea to "give her an opportunity to make up her own mind from the epicentre of the story".
She later tweeted that she was not going to Crimea, without giving a reason.