North Korea warns of strike on Seoul's presidential palace

FILE - In this Jan. 13, 2016, file photo, South Korean President Park Geun-hye addresses the nation during her news conference at the Presidential Blue House in Seoul, South Korea. Upping its rhetoric a notch, North Korea warned Saturday, March 26, 2016, that it will attack Seoul’s presidential palace unless it receives an apology from South Korean President Park for “treason.” The warning is the latest threat against Washington and Seoul over joint U.S.-South Korean military drills now underway that the North sees as a dress rehearsal for invasion. (Kim Hong-ji/Pool Photo via AP, File) (The Associated Press)

PYONGYANG, North Korea – Upping its rhetoric a notch, North Korea has warned that it will attack Seoul's presidential palace unless it receives an apology from South Korean President Park Geun-hye for "treason."

The warning is the latest threat against Washington and Seoul over joint U.S.-South Korean military drills now underway that the North sees as a dress rehearsal for invasion.

The ultimatum, issued by a unit of the Korean People's Army and carried by the North's state media Saturday, also demanded that Park publicly execute officials responsible for what it says are plans to attack its leadership.

Separately on Saturday, a North Korean propaganda outlet posted a video depicting a nuclear attack on Washington, D.C.

The heightened tensions come as the U.S. and South Korean militaries conduct their biggest joint drills ever.