U.S. Sen. John McCain has received the Liberty Medal and says the world still looks toward American leadership.
The six-term Republican senator from Arizona spoke Monday in Philadelphia as he accepted the National Constitution Center's medal for his "lifetime of sacrifice and service" to the country.
McCain says the country has a moral obligation to spread the values of the Constitution and he's humbled to join the ranks of past winners.
Democratic former Vice President Joe Biden presented McCain with the award.
McCain joined the Navy in 1958 and rose to the rank of captain during his 22 years of service. In 1967, McCain's plane was shot down over Hanoi, Vietnam, during a bombing mission. McCain spent years in a Vietnamese prisoner of war camp.
McCain recently revealed he's fighting brain cancer.
