Even a Twitter-holic such as Donald Trump will no doubt be aware that firing someone by tweeting his dismissal will be embarrassing for the person ousted from his job. And yet he did it.

Even if the US Secretary of State Rex Tillerson knew his days in office were numbered, it was humiliating for him to lose his job in such a way, especially since he was on an official trip overseas.

To some extent, Trump was probably repaying the embarrassment caused him by his top diplomat, since Tillerson was vocally at odds with him on many issues.

About 35 officials holding key posts have left the White House since Trump's inauguration, including some of his erstwhile allies. No more evidence is needed to prove that what Trump seeks is not unity but subservience.

If Tillerson's successor Mike Pompeo is to avoid his predecessor's fate, he should act as a mouthpiece echoing the president and seek to help materialize his boss' words.

Pompeo has won Trump's trust through close contact with the president in his role as CIA director, and has reflected the president's stance on issues that sowed discord between his predecessor and the president.

Although, as many cases have shown, Pompeo is a man of strong and outright views, he has never ever put a foot wrong by saying anything that might upset Trump.

Pompeo has no choice but to act as a loyal executor of Trump's directives if he wants to avoid the fate of his predecessor, as any going off-course might irritate Trump. This will greatly embolden Trump in going his own way as they will be nobody to suggest an alternative course of action.