Washington (CNN) Sexual assaults across the US military increased by a rate of nearly 38% in 2018, according to a report released by the Pentagon on Thursday.

The report which surveyed both men and women from the Army, Navy, Air Force and Marines estimated that 20,500 members of those services experienced "unwanted sexual contact" in 2018, a significant increase from 14,900 when the military last conducted a similar survey in 2016.

Unwanted sexual contact was characterized in the report as running along a range of instances from groping to rape.

In a letter to senior officials across the Defense Department on Thursday, acting Defense Secretary Patrick Shanahan announced additional steps the Pentagon would take to try and actively reduce and attempt eliminate what has been a major issue for years.

"To put it bluntly, we are not performing to the standards and expectations we have for ourselves or for each other. This is unacceptable," Shanahan wrote in the letter. "We cannot shrink from facing the challenge head on. We must, and will, do better."

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