The United States on Saturday formally recognized South Sudan as a sovereign independent state, with President Barack Obama welcoming the "birth of a new nation", dpa reported.
"Today is a reminder that after the darkness of war, the light of a new dawn is possible," Obama said in a statement released by the White House.
"This historic achievement is a tribute, above all, to the generations of southern Sudanese who struggled for this day," the president said.
Obama called on Sudan and South Sudan to "move beyond a bitter past and resolve differences peacefully" in order to ensure security and prosperity.
"Lasting peace will only be realized if all sides fulfill their responsibilities," he added.