Iran Press/ America: Citing three defense officials, NBC News had reported earlier in the day that Esper had "prepared his letter because he is one of the Cabinet officials long expected to be pushed out after the election".
Esper is helping lawmakers draft legislation to remove Confederate names from military bases, which could lead to a further rift between him and President Donald Trump, the report said.
For months, US media has been reporting about the President's frustration with Esper, who opposed using active-duty troops against civil unrest in June when Trump threatened to send military forces to crack down on nationwide demonstrations against racial injustice.
At a press briefing in August, when asked if he would fire Esper, Trump said that he "considers firing everybody".
Esper took office as the 27th US Defence Secretary in July 2019.
His predecessor Jim Mattis left office in December 2018 after clashing with Trump over the withdrawal of US troops from Syria.
104/221
Read More:
US Defense Secretary Esper has prepared a resignation letter, officials say
US troops pullback from Afghanistan
US top officials says no evidence for support Trump's claim on embassies
