Trump turns on deputy attorney general Rod Rosenstein in new 'witch hunt' tweet

President Donald Trump lashed out at his deputy attorney general Friday morning on Twitter.

The president tweeted a complaint against Rod Rosenstein, who wrote a letter justifying Trump's decision to fire FBI director James Comey -- which has now triggered an obstruction of justice investigation.

"I am being investigated for firing the FBI Director by the man who told me to fire the FBI Director! Witch Hunt," Trump tweeted.

Rosenstein issued an unusual -- and possibly pre-emptive -- statement Thursday night warning Americans not to trust anonymously sourced stories from foreign officials.

“Americans should exercise caution before accepting as true any stories attributed to anonymous ‘officials,’ particularly when they do not identify the country — let alone the branch or agency of government — with which the alleged sources supposedly are affiliated,” the statement reads. “Americans should be skeptical about anonymous allegations. The Department of Justice has a long-established policy to neither confirm nor deny such allegations.”

Rosenstein is overseeing the Justice Department probe of the Trump campaign's ties to Russia after Attorney General Jeff Sessions recused himself due to his own undisclosed meetings with the Russian ambassador were revealed.

Trump has insisted he was not under investigation in connection with the probe, but he appeared to confirm he has been a target for months after reports revealed the president was under investigation for obstruction after firing Comey.

Rosenstein told the Senate Appropriations subcommittee this week that he would not follow an order by the president to fire special counsel Robert Mueller, who he appointed to investigate possible Russian interference in the election, unless he believed there was good cause to do so.

"I'm not going to follow any order unless I believe those are lawful and appropriate orders," Rosenstein told lawmakers. "Special counsel Mueller may be fired only for good cause, and I am required to put that cause in writing. That's what I would do. If there were good cause, I would consider it."

"If there were not good cause, it wouldn't matter to me what anybody says," he added.

Some of Trump's conservative allies have urged the president to fire Mueller and questioned the special counsel's integrity and fairness.

"Mueller and Rod Rosenstein? Recuse themselves, resign immediately,” said Fox News host Sean Hannity, broadcasting live Wednesday from the baseball field where two GOP congressmen were shot and wounded hours earlier. "This is the biggest act — I want you to pay attention — of retribution we have ever seen from the deep state in the history of this country. Just as we have been saying on this program, it has now turned into a political witch hunt against the president of the United States."