Biden vowed to "immediately fire" officials who acted disrespectfully or despised colleagues, whatever the reason.

"I'm not kidding: If you work with me and I find out that you are treating your colleagues disrespectfully or look down on others, I pledge to fire you right away.

The warning was issued by Biden when presiding over the officials' online oath ceremony.

"Everyone has a right to be treated with dignity and respect, which has disappeared over the past four years," he continued, seemingly referring to the Trump administration.

"We will be assessed for this government's ability to restore the integrity and capacity of this government, so I really need your help," he added.

Biden recounts an interview with Chinese President Xi Jinping in which Xi asked: "Can you define America for me?"

The new president tells the staff they are what he is capable of.

"I will definitely make a mistake. When I make a mistake, I will admit it, and I need you to help me correct it. We will not avoid it. We will take responsibility. That's how we do it.

According to Biden's plan for the first 10 days of his tenure, the new US President aims to resolve the four crises that the US is facing simultaneously, including Covid-19, economy, climate and ethnic equality.