President Donald Trump has arrived at Walter Reed National Military Medical Center for his third checkup with his physician since November as Americans continue to express doubts about his mental fitness ahead of his 80th birthday.Trump arrived at the Bethesda, Maryland facility at 8:52 am on Tuesday for what the White House described as “his annual dental and medical evaluations” as well as visits with military personnel while there. The White House said he would undergo “routine annual dental and medical assessments as part of his regular preventive health care.”More follows...