Former CIA Director John Brennan slammed President Donald Trump as a ‘snake-oil salesman’ who has shown ‘mean-spirited, malicious, and highly abnormal behavior’ that has prompted him to speak out.

The nation’s former top spy under then-President Barack Obama said the current commander-in-chief ‘lies routinely to the American people without compunction’ while ‘intentionally fueling divisions.’

Brennan writes in an op-ed for The Washington Post that Trump’s election ‘dealt a serious blow’ to ‘the esteem with which I held the presidency.’

‘Almost immediately, I began to see a startling aberration from the remarkable, though human, presidents I had served,’ Brennan wrote.

Former CIA Director John Brennan slammed President Donald Trump as a ‘snake-oil salesman’ who has shown ‘mean-spirited, malicious, and highly abnormal behavior’ that has prompted him to speak out

‘Mr. Trump’s lifelong preoccupation with aggrandizing himself seemed to intensify in office, and he quickly leveraged his 1600 Pennsylvania Ave. address and his Twitter handle to burnish his brand and misrepresent reality.’

Trump ‘charts his every move according to a calculus of how it will personally help or hurt him,’ Brennan writes.

‘His strategy is to undercut real, potential and perceived opponents; his focus is to win at all costs, irrespective of truth, ethics, decency and — many would argue — the law,’ according to the former CIA director.

Brennan says that Trump is showing a ‘growing interest’ in ‘destroying [the] mandate]’ of Special Counsel Robert Mueller’s investigation into alleged Russian meddling in the 2016 elections.

Brennan also writes that Trump reminds him of ‘demagogues’ who ‘routinely relied on lies, deceit, and suppression of political opposition to cast themselves as populist heroes and to mask self-serving priorities.’

Brennan writes: ‘By gaining control of intelligence and security services, stifling the independence of the judiciary and discrediting a free press, these authoritarian rulers followed a time-tested recipe for how to inhibit democracy’s development, retard individual freedoms and liberties, and reserve the spoils of corrupt governance for themselves and their ilk.

Brennan also writes that Trump reminds him of ‘demagogues’ who ‘routinely relied on lies, deceit, and suppression of political opposition to cast themselves as populist heroes and to mask self-serving priorities.’

‘It never dawned on me that we could face such a development in the United States.’

Brennan, who has been criticized by other intelligence officials for making overt political comments, said he will ‘continue to speak out loudly and critically until integrity, decency, wisdom - and maybe even some humility - return to the White House.’

Trump and his allies on Fox News have attacked Brennan and other top national security officials in the Obama administration for ‘planting spies’ in the Trump campaign to cook up an investigation into alleged collusion with Russia.

Last month, Trump went after Brennan, calling him the 'genesis' of the Russia probe and saying he 'disgraced himself.'

The attack came after Brennan has spent weeks sharpening his own criticism of Trump – including calling Trump's latest demand for a Justice Department investigation of the FBI over its Russia probe a 'disastrous path' for the president.

'This guy is the genesis of this whole Debacle,' Trump vented Monday morning, after he demanded the Justice Department probe whether the FBI 'infiltrated or surveilled the Trump campaign.'