The charges surfaced in April, shortly after four-star General John Hyten was named the second military advisor to the president.
The official stated that no evidence or information had been found to support nine allegations made against Hyten by a young officer.
Two senior army officers confirmed to CNN that the officer had already made similar allegations against other staff members.
The Pentagon issued a statement in which it stated: "After a thorough investigation by the Air Force Special Investigations Office, there was insufficient evidence to support a possible misconduct by General Hyten." General Hyten cooperated with the investigation. With more than 38 years of service to our nation, General Hyten has revealed a principled and dedicated patriot. "
CNN was not able to speak to the officer who made the allegations against Hyten.
It was asked why a confirmation hearing for Hyten had not yet been scheduled, three months after his appointment for the post.
Hyten, who would succeed General Paul Selva, is currently leading the US strategic command, which plays a key role in monitoring nuclear tests and missile launches around the world and advises the president, if any, on nuclear launch options for the US.
Officials told CNN that the allegations had caused the dismay of dozens of officers, who did not know whether the administration would still support Hyten's candidacy. It is also questionable whether Hyten will want to hold a public confirmation hearing to discuss the allegations even if the army has cleared them.
Members of the Senate Armed Services Committee were informed of the results of the investigation on Wednesday morning. After this briefing, a small number of journalists were also informed of the outcome.
In a letter dated June 25 to the Defense Secretary Mark Esper, Democrats. Elizabeth Warren and Tammy Duckworth – both members of the committee – criticized how the Air Force handled the case, saying a criminal investigation raises serious questions about whether the department grants preferential treatment to General Hyten because of his rank and his pending appointment. "
It is unclear whether Wednesday's statement dispelled the concerns raised in the letter, but a Senate staff member confirmed that the Hyten accuser had contacted members of the committee.
CNN contacted committee members for their reaction to the meeting but did not receive an answer.
The Pentagon has not issued any official statement on the status of Hyten's candidacy. "We have not received any changes to its status," said Pentagon spokesman Colonel DeDe Halfill.
The news of the investigation comes as the Pentagon continues to operate without a Defense Secretary confirmed by the Senate. Many other senior positions in the military are still vacant or are filled by officials in acting roles.
These positions are a reflection of the Department of Defense's fierce fight to put in place an unprecedented transition plan to ensure continuity of leadership at the highest levels, while there is still no Defense Secretary confirmed after the dramatic implosion of Patrick Shanahan's appointment last month.
Nine allegations made
The investigation examined the policewoman's allegations concerning nine incidents that occurred between February 2017 and February 2018. The senior military official stated: "In early April, we received allegations of abusive sexual contact and inappropriate relations against General Hyten" after "his appointment was made public.The Air Force Special Investigations Bureau opened a criminal investigation on April 15."
The official noted that the criminal investigations did not take a position to corroborate the allegations, but simply report evidence and facts learned. The evidence and the facts were then reported to another four-star general who reviewed the report and who was entitled to convene a court martial or initiate disciplinary action. This officer – General James Holmes, chief of the Air Combat Command – refused to take action, finding that the evidence and facts were insufficient to corroborate the allegations.
"The convening authority of the court martial examined the facts set out in the report and, in the opinion of their lawyer, ruled that there was not enough evidence to accuse General Hyten or to recommend an administrative action against the general, "told reporters.
The senior official was adamant that the woman's allegations had been taken seriously and that the procedures had been followed. Moreover, there was no evidence to reassign Hyten during the investigation.
"We looked at each of the leads that were provided to us.We looked at each of the stones for which we thought we should examine the principle of sufficiency of the investigation, as a practice, said that you might want to do this. or yourself, so far, we've looked at it, "said another senior official.
"At this point, we conducted a thorough investigation, interviewed 53 witnesses from three countries and 13 states, reviewed tens of thousands of e-mails, interviewed the people closest to the alleged incidents, and we are just a stone's throw away. 'is also comprehensive,' they added.
Ryan Browne of CNN contributed to this report.