United States President Donald Trump removed Secretary of Defense James Mattis two months before his agreed resignation and replaced him with Deputy Secretary of Defense Patrick Shanahan. The president’s decision was purportedly prompted by Mattis’ criticism of his policy on Syria.

Trump said Shanahan will take on the title of acting secretary of defence starting January 1. “Patrick has a long list of accomplishments while serving as deputy, and previously Boeing,” Trump said. “He will be great!”

Mattis had resigned on December 20, a day after President Donald Trump announced the withdrawal of US troops from Syria. Trump had said Mattis will retire in February after having served his administration for two years.

Mattis in his resignation letter to Trump had said he was leaving because “you have a right to have a Secretary of Defense whose views are better aligned with yours”.

Meanwhile, an unidentified official in Trump’s administration said the president had already signed the order to withdraw troops from Syria, CNN reported. Trump also reportedly told Turkish President Recep Tayyip Erdogan that the US was “done” with Syria during their telephone conversation on December 14, the news channel reported quoting an unidentified source.

On December 23, Trump said he discussed a “slow and highly coordinated” withdrawal of US troops from Syria. “We discussed the Islamic State, our mutual involvement in Syria,” Trump tweeted about a conversation he had with Erdogan.

The US president’s decision to remove troops from Syria was criticised by his French counterpart Emmanuel Macron, who said he “deeply regretted” Trump’s decision, Reuters reported.

Trump’s Republican party colleague and Senator Bob Corker said he was “saddened” by the decision. Corker is the chairperson of the Senate Foreign Relations Committee. “I think he knows he made a mistake,” Corker, who is retiring, told CNN. “The president’s tendencies are to dig in and double-down if he knows he has done something that is probably incorrect.”