US President Donald Trump has signed several executive orders focused on reshaping the US military.

One order signed late on Monday bans diversity, equity and inclusion (DEI) initiatives in the military. It will remove the use of race- or sex-based preferences in the armed forces, the Defense Department and the Homeland Security Department.

Another reinstates more than 8,000 service members who were discharged for refusing to get the Covid-19 vaccine.

The White House added that a third executive order tasks officials with formulating a policy on transgender troops. The action does not immediately ban transgender service members.

A fourth order mandates a process to develop an "American Iron Dome" - similar to the one used by Israel in the Middle East; while the White House says a proclamation has been signed to commemorate the 80th anniversary of the liberation of Auschwitz.

The executive orders were signed by Trump on board Air Force One.