Minutes before President Donald Trump tweeted on Friday morning that he and First Lady Melania Trump had tested positive for Covid-19, two Boeing E-6B Mercury planes showed up in public flight data—one charting a course off the East Coast of the United States and one off the West Coast. Even in pandemic times there’s nothing unusual about seeing planes on these types of paths overnight, but E-6Bs are not normal commercial aircraft. They’re used for sending ballistic missile commands.

After news broke on Thursday that Trump advisor Hope Hicks had tested positive for the novel coronavirus, plane spotters and social media prognosticators drew a connection to the E-6Bs they saw taking off. Perhaps, they suggested, it was an indication that Trump had tested positive, and during this delicate moment US Strategic Command was working to send a message of deterrence to its adversaries. The idea went viral, heightening confusion and fear about the implications of Trump’s diagnosis.

The truth is that while they are exceptionally interesting planes, E-6Bs take off, fly, and land regularly as part of the US missile defense apparatus. They need to be ready at a moment’s notice, so they are.

“I can confirm these flights were pre-planned missions,” US Strategic Command media operation chief Karen Singer told WIRED on Friday. “Any timing to the president’s announcement is purely coincidental.”

E-6Bs, which are based on Boeing 707s, are essentially communication relay stations built to receive military orders from the president of the US and the secretary of defense, and then convey those commands to US ballistic missile submarines. They’re also equipped to remotely control Minuteman intercontinental ballistic missiles through a platform called the Airborne Launch Control System. The idea is for E-6Bs to serve as a redundancy in case ground-based communication systems are disrupted. And they’re also crucial for establishing line-of-sight communication connections that require proximity. The E-6B mission overall is known as TACAMO, or Take Charge And Move Out.

“These aircraft take off all the time, I certainly didn’t draw any conclusions from it,” says Jeffrey Lewis, director of the East Asia Nonproliferation Program at the Middlebury Institute for International Studies in Monterey, California.

The planes have some dramatic capabilities. One of the most significant is their Very Low Frequency communication platform, which is used to reach nuclear ballistic missile submarines down to 60 feet below the ocean’s surface. These stealth submarines must conceal their positions and often can’t rise to shallower depths or send up buoys to aid communication. Instead, both communication relay planes and the submarines themselves must be equipped with massive antennas, and even then VLF systems are still extremely low latency, low bandwidth, and low throughput, meaning it takes a long time to send very small amounts of data.

To transmit even the shortest messages to deep sea submarines, E-6Bs perform special airborne maneuvers. These are essentially steep, tight turns that go on for long periods of time looping the plane around and around to get the antennas in a vertical position transmitting straight down into the water. Other military planes are also equipped for VLF communication, but it is especially core to the mission of E-6Bs.

Though E-6Bs aren’t constantly flying as part of Strategic Command’s Airborne Command Post, their predecessor plane, the Air Force EC-135, was part of a mission that had at least one plane in the air at all times for more than 29 years from February 3, 1961 so July 24, 1990. Coverage may not be that constant today, but readiness exercises are still extremely common.

“On a day to day basis, people don’t think about the fact that the United States is postured to use more than 1,000 nuclear weapons on a few minutes notice,” the Middlebury Institute’s Lewis says. “They just don’t think about that, because that seems crazy. And so when something happens and people look and they see the normal readiness level they think to themselves, ‘oh my god, this must be a catastrophe, because why would you have all these forces on alert?!’ But Trump getting sick didn’t cause this, this is what it’s like all the time. And if you don’t like that then maybe that’s a conversation to have.”

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