Obama even sprinkled a bit of cold water on the Swedish Nobel poohbahs in his acceptance speech, cautioning that he might have to fight some wars- Good Wars, of course, wars of necessity. (What other kind is there? Throughout history empires have "needed" to conquer and subjugate to add to their wealth, for example. The Third Reich needed to defend "Western Civilization" from the Jewish-Slavic-Bolshevik hordes from the East- they actually said this, and citizens from all over Western Europe and Scandinavia rallied to the cause, joining the Waffen-SS, and helping round up Jewish vermin for extermination in their home countries. War is always "necessary.")
In what in hindsight looks like preordained irony, the 1999 Prize went to Médecins Sans Frontières (Medicine Without Borders), whose hospital in Kunduz, Afghanistan, Obama would later bomb as president, murdering medical staff and patients. After MSF complained about it, Obama sent a tank crashing through its gates. Yes, Obama did it. First, he is Commander in Chief of the U.S. armed forces, as specified in the U.S. Constitution. Thus under the doctrine of command responsibility, he is ultimately responsible. Second, he granted the armed forces the leeway to commit such war crimes and atrocities. And they certainly wouldn't have engaged in the second attack days later without the okay from Obama. Thirdly, it is quite possible that such a crime was either initiated by Obama or the Pentagon ran it by him first. MSF had repeatedly given the U.S. military the precise GPS coordinates of its hospital location, so as to avoid any "accidental" attacks. The same foolish thing that Al-Jazeera does, which has facilitated repeated U.S. attacks on its offices. (British Prime Minister and smarmy criminal Tony Blair had to talk then-president George Bush out of bombing Al-Jazeera's headquarter in Qatar, where it is based!) 
Other U.S. presidents have had the noble Nobel bestowed upon them. Jimmy Carter in 2002, 22 years after he left office, for the vague reason of "his decades of untiring effort to find peaceful solutions to international conflicts, to advance democracy and human rights, and to promote economic and social development." And the very militaristic and rabidly war-mongering Theodore Roosevelt, in 2006, who at least arguably did something involving creating some actual peace, namely brokering an end to the Russo-Japanese war.
The problem with the Nobel Peace Prizes is that giving them out to so many execrable scumbags (there's a long list, but each one would require an explanation) devalues the legitimate recipients, and there certainly are some of those. In addition to prestige, the prize isn't a mere medal, but comes with 9 million Swedish kroner, about $1,110,000 U.S. at today's exchange rate.
Martin Luther King, Jr., received the Prize in 1964. The FBI tried to blackmail him into committing suicide before accepting it, using surreptitiously-made recordings of his sexual dalliances. By 1968 the U.S. power structure had had enough of him (the Washington Post and New York Times, major organs of and soapboxes for elite opinion, both excoriated him for his opposition to the Vietnam War, and his involvement in labor struggles also marked him as a threat) so the CIA murdered him, with the help of the Memphis police, the FBI playing its usual role of cover-up disguised as "investigation," and the entire U.S. establishment media and power system acting as accomplices to this day.