Obama: This was my worst mistake

President Barack Obama believes that the biggest mistake of his presidency was not having a plan for Libya after the overthrow of Moammar Gadhafi in 2011.

In a Fox News Sunday interview, Obama was asked what he believed was the worst misstep during his time in the White House.

"Probably failing to plan for the day after what I think was the right thing to do in intervening in Libya," he said.

Obama said in The Atlantic's April cover story that the lack of preparation for a post-Gadhafi Libya contributed to the country's current "mess."

Since a NATO-backed revolt ousted Gadhafi, Libya has slipped deeper into turmoil, with two rival governments and a range of armed factions locked in a struggle for control of the OPEC state and its oil wealth.

In the chaos, Islamic State militants have grown in strength, taking over the city of Sirte and launching attacks on oilfields.

— Reuters contributed to this report.

Read the full interview transcript on Fox News.