Washington ( CNN ) -- Before President Obama says a word during his Tuesday Oval Office address , the backdrop will make a statement for him : that he is the decider . Obama is set to give his second Oval Office address , a speech meant to mark the end of combat missions in Iraq . But besides the remarks he will make , the setting of his speech will convey something , too . `` The Oval Office invokes the center of the presidential authority . That 's the president 's office , that 's where he supposedly makes decisions , where he governs , '' says presidential historian Robert Dallek . `` [ When ] a talk to the nation is given from that office , [ it ] is underscoring his executive powers , his leadership . '' The Oval Office symbolizes power , command , and authority , Dallek said . It shows the president , `` as George W. Bush put it , is the 'decider ' `` and that symbolism is important . For example , former President George H.W . Bush announced the start of the first Gulf war from the Oval Office , telling Americans and the world that he was the commander in chief just by setting the scene in the Oval Office . And on the night of the terrorist attacks on September 11 , 2001 , former President George W. Bush spoke to the American people from the Oval Office , to show he was in command and to reassure the nation . Dallek points out the differences between giving a speech in the Oval Office versus a speech in a different venue . For example , Obama 's speech in front of the joint session of Congress a year ago conveyed his desire to get Congress to act on health care reform . `` A joint session of Congress has a different function , '' Dallek said . A speech in front of both the Senate and House shows the president is `` trying to convince Congress to join with him . '' When Obama addressed both chambers in September 2009 , the health care debate was still waging . He called for bipartisan proposals to address health care reform and focused attention on the issue , on Congress and on the presidency . An Oval Office address is different . The prime-time address focuses the attention singularly on the subject matter . `` Presidents do n't give speeches from the Oval Office casually , '' Dallek said . `` It 's given with forethought and consideration . So the fact that he 's giving the current speech about the end of America 's combat role in Iraq is something that he wishes to emphasize and underscore and in a sense I think it 's a demonstration of his completion of his mission or fulfillment of a commitment that he made . '' Because of the singular focus on the subject matter during Obama 's Tuesday evening address , Obama will have to navigate the tricky road of marking the end of a war he did not support and honoring the lives of all the Americans killed in the war , Dallek said . Obama must use a `` certain amount of domestic diplomacy to bring the war to a close ; you do n't just end the war and say it 's a mistake . It 's unpalatable because of all the deaths , '' Dallek said . So Obama must do it in a way that is `` politically palatable to the American public -- that is at the heart '' of his address Tuesday , Dallek said . The Oval Office will also help convey a sense of intimacy of the message . Since former President Jimmy Carter , each president has delivered his farewell address from that room , using the office of the presidency to say goodbye to the American public . President Reagan used the intimate space to comfort the public after space shuttle Challenger exploded in 1986 . President Johnson used the room in 1968 to tell Americans he would not seek re-election and President Nixon gave several speeches regarding the Watergate scandal , including his decision to resign from the presidency in the wake of Watergate in 1974 . Obama 's other Oval Office address was two months ago to address the nation about the Gulf oil disaster . And who does the presidential historian think was most successful at intimate talks to the American people ? Franklin Roosevelt 's fireside addresses -- although there were no televisions at the time , these radio talks were effective in boosting the country 's confidence .
Obama to give Oval Office address on end of his mission in Iraq . Presidents do n't give address from the Oval Office casually , said Obama . Obama 's other Oval Office address was two months ago .