The US Army's artillery capabilities offer unparalleled flexibility in combat situations, providing essential support to US and allied forces worldwide.

The US Army operates two primary howitzer-class systems: the M777 and the M109A7.

The US military defines howitzers as any cannon artillery capable of both high-angle (45° to 90° elevation) and low-angle (0° to 45° elevation) fire.

Their long range and adjustable firing angles make howitzer-class systems highly flexible in combat.

Both the M777 and the M109A7 Paladin can fire rocket-assisted projectiles designed to increase range and speed and Excalibur 155mm extended-range guided artillery shells.

The Excalibur shells are Global Positioning System-guided, and the M109A7 can fire them at a range of 40 to 48km, giving the gunners distance and protection. Excalibur shells have been used around the world, from India to Sweden.

The M777

The M777, a 155mm caliber, lightweight towed howitzer, is in service across the world, used by the ground forces of Australia, Canada, Colombia, India, Saudi Arabia, Ukraine and the United States.

The US Marine Corps, Army and Army National Guard all operate the M777 howitzer system. It entered service in 2005 during the Afghan war.

It packs all the power of its 7,300kg predecessor, the M198, into a 3,400kg package. Its lightness makes it a far more maneuverable towed cannon weapon, allowing forces to transport it by truck, cargo aircraft or helicopter without impacting range or accuracy.

The M777 can fire four rounds per minute for two minutes or a sustained rate of two rounds per minute.

Its rocket-assisted range exceeds 30km, and it can strike targets regardless of terrain or obstacles.

The M109A7 Paladin

The M109A7 Paladin is a tracked, self-propelled 155mm howitzer that has been in service since 2015.

Improving on the reliability, lethality and maintainability of its predecessor, the M109A6, the M109A7 provides indirect-fire support to Armored Brigade Combat Teams and mechanized infantry divisions.

The M109A7 and Bradley Fighting Vehicle use interchangeable chassis components. The M109A7 has a faster electric drive than the M109A6 does.

The M109A7's 155mm M284 cannon, M182A1 gun mount and automated loader can fire up to four rounds per minute.

It can fire its first round from a move in under 60 seconds before moving on -- a "shoot and scoot" capability that protects the crew from counterbattery fire.

It is usually accompanied by the M992 Field Artillery Ammunition Supply Vehicle, a tracked ammunition carrier built on the chassis of the Paladin. The M992 is designed to feed rounds into the M109A7 via a hydraulic conveyor without the direct assistance of a crew member.