President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.

President Barack Obama, accompanied by Iraqi Prime Minister Nouri al-Maliki, and Vice President Joe Biden, salutes as he departs the White House en route to Arlington National Cemetery, Dec. 12, 2011. The President and Prime Minister participated in a wreath laying ceremony at the Tomb of the Unknowns. An interpreter, center, walks with the group.