The US secret to its fighters and bombers being able to fly for hours is this veteran tanker aircraft.

The United States deployed seven B-2 Spirit stealth bombers this weekend to three key nuclear sites in Iran : Fordow, Natanz, and Isfahan. The aircraft were carrying GBU-57 MOP (Massive Ordnance Penetrator) bunker-busting bombs weighing more than 30,000 pounds. While not nuclear, they are designed to destroy deeply buried and heavily protected military targets .

For all of this operation to be possible, it took an element of the U.S. Air Force that has been a fundamental part of its missions for more than 60 years: the KC-135 Stratotanker, a tanker aircraft developed by Boeing .

If its role is key, it is because it allows fighters, bombers and reconnaissance aircraft to sustain prolonged flights without needing to land .

Despite its age, this model remains in active service thanks to a series of modernizations that have allowed it to adapt to the demands of the 21st century. Now, amid escalating regional tensions, the United States has once again demonstrated its power with the deployment of at least 30 units to the Middle East, according to the BBC and Reuters . The data from these international media outlets is extracted from movements recorded on the AirNav Systems and Flightradar24 websites.

The plane that gives wings to air power

The first KC-135 flew in 1956 and entered service a year later. Since then, it has been the U.S. Air Force's primary aerial refueling aircraft. Without it, fighters, bombers, and even allied aircraft would be unable to conduct extended missions far from their bases.

Although it doesn't carry weapons or feature in action scenes, the KC-135 Stratotanker's role is so critical that it's considered a "force multiplier." And that's no exaggeration: mid-air refueling keeps fighters airborne for hours , extends operations to entire continents, and maintains mobile bases without landing.

This tanker aircraft is equipped with four high-thrust engines that allow it to reach cruising speeds of nearly 850 kilometers per hour and operate at altitudes approaching 15,250 meters, where commercial aircraft rarely fly.

Its maximum takeoff weight is 146,000 kilograms (310,000 lb), and it can carry more than 90,000 kilograms (200,000 lb) of fuel to be transferred to other aircraft during the flight. The KC-135 can also be configured to carry up to 37 people or nearly 38 tons of payload in its upper bay.

In terms of size, it's a 41.5-meter-long aircraft with a wingspan of nearly 40 meters , capable of covering more than 2,400 kilometers. Flying without external payload, its range increases to 17,700 kilometers, allowing fighters and bombers to cross continents without touching land.

The key to their success: the 'boom operators'

Watching an aircraft refuel in mid-air seems almost like science fiction, although for the KC-135 Stratotanker pilots and the fighter jets flying behind them, it's just another day at the office. But the reality is that it's a maneuver as routine as it is dangerous . It all begins long before the planes meet in the sky. Both teams coordinate the exact location, altitude, and speed of the rendezvous .

The tanker aircraft flies in a straight line, steady and at a constant speed. Minutes later, the fighter jet needing fuel appears on the horizon and approaches with pinpoint accuracy. It must position itself directly behind the KC-135, so close that, from the tanker's rear cockpit, the refueling system operator—lying face down over a window —can see every detail of the receiving aircraft's nose. They are the so-called 'boom operators' .

At that moment, the operator activates the KC-135's telescopic arm, known as the flying boom —hence the name of those who operate it—and begins to manually guide it toward a hatch on the fighter. There are no automatic sensors: everything depends on the pulse, precision, and experience of the human piloting this flying stinger.

When the boom successfully docks, the fuel transfer begins. The hose becomes an umbilical cord that keeps the fighter alive , allowing it to continue flying for hours without ever having to touch down. This all happens at over 800 km/h and thousands of meters above sea level, in mid-flight.

Once the tank is full, the boom retracts, the fighter jet smoothly detaches, and the KC-135 prepares to serve the next aircraft. Thus, one after another, bombers, fighters, and surveillance aircraft receive the fuel that allows them to cross oceans, maintain extended patrols, or execute missions without relying on a runway.

"Pole-vaulting requires a steady hand, extensive training, and nerves of steel to achieve safe contact."

An aircraft in continuous evolution

Although the first models left the factory in the 1950s, most active KC-135s have been modernized several times. The most significant change was the replacement of their aging engines. This upgrade not only reduced fuel consumption and noise, but also increased the amount of fuel that can be transferred in flight .

In addition, recent upgrades have included digital navigation systems, autopilot and advanced avionics , which have extended the KC‑135's operational life to at least the 2040s.

The KC-135 has been present in all major US military operations and has even been used by its allies.