Howitzers are long range weapons favored by the US Army and Marine Corps and have been deployed in many world conflicts. The M777 howitzer is a type of two 155mm howitzers, which can hit targets up to 18 miles away.
It is usually operated by around 10 people, part of a larger group of six guns called a battery.
The US 7th Army Training Command is instructing between 50 and 60 Ukrainian officers on the specifics of the M777 howitzers, according to new reports.
This follows previous waves of training of Ukrainian fighters by the United States on similar heavy artillery.
Last week, the US Department of Defense said about 60% of US-made howitzers shipped from America to Ukraine had reached their destination.
A US official confirmed that the howitzers were delivered with 155mm rounds.
The official said, “We believe these howitzers will be […] very, very effective in helping in the Donbass fight, which we have already seen, is deeply dependent on long-range fire, especially artillery from both sides.
They added: “We certainly believe the conditions could be set for much longer work here inside Donbass given both sides’ familiarity with the terrain.
“We described it as a potential knife fight, and I think it’s starting to become exactly that.”
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“And we know that the Russians also believe the same, because we also see them moving artillery units into Donbass.
“And so we want to give Ukrainians every advantage we can.”
Mr Kirby added: “What this provides Ukrainian forces with is lethal long-range fire that is very effective against everything from lightly armored vehicles to support vehicles, and in particular the Russian indirect fire system, their artillery and their rockets.”
A number of countries have sent M777 howitzers to Ukrainian forces since the start of the Russian invasion on February 24.
Canadian President Justin Trudeau said in a statement in April that the country had “now delivered a number of M777 howitzers and associated ammunition to Ukrainian security forces, in conjunction with our American allies.”
A few days later, Australia pledged to provide six M77 howitzers to Ukrainian forces to repel “the brutal, relentless and unlawful invasion from Russia”, Prime Minister Scott Morrison confirmed.
In a joint statement with Australian Defense Minister Peter Dutton, Mr Morrison detailed: “The new $26.7 million support to Ukraine brings Australia’s total contribution to defensive military assistance to Ukraine over $225 million.”
The Australian Army describes the M777 howitzer as a “significant advance in Army capabilities”, with a “much higher level of digital connectivity”.
This allows for “faster, safer, and more accurate application of effects in the battlespace,” according to their website.