With a range of 5,900 miles (9,500km), a top speed of Mach 1.25, and the largest weapon payload capacity in the US Air Force inventory, the B-1B Lancer is the "backbone" of America's long-range bomber force.

B-1B Lancers on February 2 took off from the United States and took part in the retaliatory strikes on dozens of targets linked to Iran's Islamic Revolutionary Guards Corps (IRGC) and affiliated militia groups in Iraq and Syria.

The targeted facilities include command and control operations centers, intelligence centers, rockets, missiles, unmanned aerial vehicle (UAV) storage, and logistics and munition supply chain facilities of militia groups and their IRGC sponsors who facilitated attacks against US and coalition forces, US Central Command said.

The supersonic heavy bomber was designed to fly at extremely low altitudes with reduced radar visibility, including mountainous terrain at Mach speeds or below 200 feet, according to the US Air Force.

Known as the "Bone," the B-1B holds around 50 world records for speed, payload, range and time of climb in its class. It is a four-man crew aircraft with a pilot, co-pilot, weapons officer, and defense systems officer.

According to the Air Force, the Lancer can "rapidly deliver massive quantities of precision and non-precision weapons against any adversary, anywhere in the world, at any time," and has the largest internal payload capacity of any US Air Force bomber.

This capability, in addition to the many other land, sea and air assets of the US military, enables the United States to help its allies in times of need against common adversaries.

"We have the largest payload, we have the speed to get to where we need to get to, we have the loiter time to hang out once we're there," Lt. Col. Dominic "Beaver" Ross, director of operations for the 337th Test and Evaluations Squadron, told Military.com in 2017.

The B-1B is capable of carrying up to 75,000 pounds (34,000kg) of ordnance in three internal weapon bays that can be loaded with a variety weapons, including the Mark 80-series bomb, according to the Air Force Armament Museum.

The Mark 82 (Mk82), the 500-pound (226kg) variant, is one of the most commonly used and can be converted into different variants such as the Quickstrike naval mine, the Guided Bomb Unit (GBU)-12 laser-guided bomb and the GBU-38 Joint Direct Attack Munition (JDAM).

JDAM is a guidance kit that converts unguided, free-fall bombs like the Mark class into "accurate, adverse-weather 'smart' munitions," according to the Air Force.

The upgraded Laser JDAM (LJDAM) contains a global positioning system (GPS) guidance control unit, capable of precision guidance and attack of stationary and moving targets.

"Once released from the aircraft, the JDAM autonomously navigates to the designated target coordinates," the Air Force says.

With GPS data activated, the JDAM is capable of hitting a target with a margin of error of five meters or less.

Each of the B-1B's three internal bomb bays can carry up to 16 500 lbs JDAMs for a total of 48.

The B-1B, which achieved initial operational capability in 1986, is still undergoing upgrades.

As part of the B-1 Embracing Agile Scheduling Team (BEAST) program, a number of the aircraft over the next two years are receiving a modernized Identification Friend or Foe system, Link 16 tactical data communications capability, upgraded secure communications systems, an updated defensive avionics system, and updated mass data storage.

The first modernized aircraft made its first flight in October.

The BEAST modifications should give the B-1 "life and lethality out to 2040 and beyond," Air Force officials have said.

Less flights, more bombs

The US Air Force maintains a force of 45 B-1B bombers.

The aircraft first saw combat in support of operations against Iraq during Operation Desert Fox in December 1998, according to a US Air Force fact sheet.

In 1999, six B-1s took part in Operation Allied Force, delivering more than 20% of the total ordnance while flying less than 2% of the combat sorties.

Similarly, during the first six months of Operation Enduring Freedom, eight B-1s dropped nearly 40% of the total tonnage delivered by coalition air forces, including nearly 3,900 JDAMs, or 67% of the total.

In Operation Iraqi Freedom, the B-1B flew less than 1% of the combat missions while delivering 43% of the JDAMs used, according to the Air Force.

More recently, two B-1Bs took part in a high-profile strike in April 2018, firing air-launched cruise missiles against multiple Syrian government sites as reprisal for the Douma chemical attack against civilians a week earlier.

B-1 Lancers are still conducting missions in the skies of the Middle East, demonstrating the ability to rapidly project combat power.