The US military reported Thursday a slight drop in cases of sexual assault in its ranks, a first in almost 10 years and on the heels of Pentagon reforms.

Prevalence fell five percent in fiscal year 2023 compared to the previous year, from 8,924 to 8,515 cases reported to the US Department of Defense, which employs or supervises some 3.4 million military personnel and civilians.

The figure has been increasing almost constantly since 2011, with only one slight decrease in 2015.

Notably, the estimated prevalence is also decreasing: 6.8 percent of female soldiers and 1.3 percent of men indicated having experienced "unwanted sexual contact" in the previous year, compared to 8.4 percent and 1.5 percent respectively two years earlier.

The study that produces the figures, carried out every two years by survey, helps tackle under-reporting of cases of sexual violence: only 25 percent of cases are reported, compared to 20 percent two years ago.

Cases of sexual harassment are also declining, according to this report.

The results "demonstrate that the Department is making progress to prevent sexual assault and harassment in the military," Defense Secretary Lloyd Austin said in a statement.

"These early findings are encouraging," he added, stressing that there was much more work to be done.

Since 2023, the management of cases of sexual violence within the US army has been handled by special prosecutors, independent of the military hierarchy, a reform launched by President Joe Biden.

An independent commission of inquiry estimated in 2021 that 20,000 soldiers suffer sexual assault each year, less than 8,000 report this assault and less than 5,000 request an investigation, and only a small number lead to military justice action.