Updated

Two Boeing E-6B Mercury planes were detected flying along both coasts of the U.S. mainland early Friday, around the time President Trump announced he and first lady Melania Trump were diagnosed with coronavirus -- but the flights were “pre-planned” and the timing was “purely coincidental,” a U.S. Strategic Command spokesman told Fox News.

A senior defense official also told Fox News there has been “no change to the posture of the U.S. military,” adding, “The president remains the commander-in-chief.”

Trackers on social media noted that one Boeing E-6B Mercury was flying along the East Coast and another was spotted in the air above Oregon.

The E-6B is used by the government to convey instructions to the fleet of ballistic submarines the U.S. has in waters around the world. The vessels can deploy nuclear-tipped Trident submarine-launched ballistic missiles (SLBMs).

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The planes are part of Operation Looking Glass – known today as Airborne Command Post (ABNCP) – and are used to provide command and control of U.S. nuclear forces if any ground-based command centers are either destroyed or inoperable.

The Boeing E-6B is a an airborne command post and communications relay used to send orders to U.S. nuclear submarines. (Photo: Naval Air Systems Command)

There was speculation the airborne command posts were deployed as a warning to any of America’s enemies after news broke of Trump’s positive test for the novel coronavirus.

The U.S. Navy, which operates a fleet of 16 E-6Bs, normally has at least one of the planes in the air at all times and it is not uncommon for two of the four-engine planes to be in flight.

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While military planes generally turn off their transponders in order to avoid being tracked, the two E-6Bs in the air early Friday morning had left theirs on, with the assumption being that their crews want to be seen.

“It's a message to the small group of adversaries with SLBMs and [intercontinental ballistic missiles],” Tim Hogan, a noted open-source intelligence practitioner, tweeted.

Fox News' Lucas Tomlinson contributed to this report.