OMAHA (VINnews) – One of the U.S. military’s E-4B Nightwatch “doomsday planes” took off Monday from Offutt Air Force Base in Nebraska and circled the area for hours, flight trackers showed, as President Donald Trump’s deadline for Iran to accept a peace deal approached.

The Boeing E-4B, designed to serve as an airborne command post for national leaders in the event of nuclear war, departed Offutt at 10:17 a.m. EST. It circled the base at least six times before landing, according to flight tracking data reported by the Daily Mail.

Offutt Air Force Base serves as headquarters for U.S. Strategic Command, which oversees the nation’s nuclear forces.

The flight comes as Trump has set a Tuesday deadline for Iran to agree to his peace plan and reopen the Strait of Hormuz, or face U.S. strikes on the country’s power plants and bridges. Trump has weighed expanded military action against Iran amid ongoing tensions.

The U.S. maintains a fleet of four E-4Bs for continuity of government operations. Each aircraft can carry up to 112 people, has a range exceeding 7,000 miles and features thermal and nuclear shielding. It is equipped with 67 satellite dishes and antennas for global communications.

Similar E-4B flights have drawn attention during past periods of heightened U.S.-Iran tensions, including one last year ahead of joint U.S.-Israel strikes on Iranian nuclear sites. The planes conduct regular training flights year-round to maintain readiness.