Gen. John E. Hyten’s chances of being confirmed as the military’s second-highest officer may come down to one thing this week: whether senators believe an Army colonel’s ­charges that he sexually assaulted her while she was under his command — accusations he denies.

Col. Kathryn Splet­stoser has accused Hyten, who is currently responsible for the country’s nuclear arsenal as the head of U.S. Strategic Command, of making unwanted sexual contact with her on several occasions in 2017 while the two were traveling for work.

Both Democrats and Republicans on the Senate Armed Services Committee maintain that her account is plausible, but some members have also said they are wary of taking her uncorroborated word over the categorical denials of a decorated four-star Air Force general endorsed by high-ranking colleagues.

The Air Force’s Office of Special Investigations investigated Spletstoser’s allegations but could not substantiate her claims. In a statement, U.S. Strategic Command spokesman Bill Clinton said the command had “fully cooperated” with the probe, noting that Air Force officials found that “there was insufficient evidence to support any finding of misconduct on the part of Gen. Hyten.”

Former Air Force secretary Heather Wilson, who was briefed on investigators’ findings before leaving her position earlier this year, said in an interview Sunday that “the Air Force left no stone unturned in its investigation and the Senate has been thorough as well.”

“Based on what I know of the complete investigation,” she continued, “I believe General Hyten was falsely accused.”

Now questions about the integrity of that probe, conducted after President Trump nominated Hyten to serve as vice chairman of the Joint Chiefs of Staff, are putting the high-stakes case of he-said-she-said to a Senate with little experience adjudicating these matters — save for last year’s politically charged hearing for Supreme Court Justice Brett M. Kavanaugh, at which Christine Blasey Ford testified that Kavanaugh sexually assaulted her while they were both in high school.

“I don’t think there has been a separate effort in the Senate to try to determine some way of responding to individual nominees when this issue has come up,” said Sen. Jeanne Shaheen (D-N.H.), a member of the Senate’s Armed Services and Ethics committees. “That affects how people decide to vote, one way or another.”

Senators may have to cast their vote soon: The chairman of the Armed Services Committee, Sen. James M. Inhofe (R-Okla.), has scheduled Hyten’s official public confirmation hearing for Tuesday, the last step before the panel and then the full Senate vote on his confirmation. Spletstoser said the committee has denied her request to speak at the hearing, unless she has “new information” to present.

Spletstoser’s public remarks would probably mirror much of what she has told the panel in private and alleged in a Washington Post interview: that Hyten had taken a liking to her when he took over U.S. Strategic Command in November 2016, picking her to be his “point person,” but that two months in, he started making overt and unwelcome advances during official overnight trips.

The first time was in January 2017, she alleges, when Hyten grabbed her left hand as she was exiting a work meeting in his hotel room in Palo Alto, Calif., pulling it in toward his groin so she could feel his erection before she moved her hand away. In June 2017, Spletstoser said, Hyten interrupted a work meeting in his Washington, D.C., hotel room to fondle her breasts and kiss her — and she pushed him away and admonished him, she said. That prompted Hyten to panic, she said, and ask her through tears: “Are you going to tell on me?” Though she felt he had clearly “crossed a line,” she assured him she would not, she said.

Yet it was during the Reagan National Defense Forum in December 2017 that Spletstoser said Hyten made his most aggressive move, arriving uninvited at her hotel room in workout clothes carrying a binder, and claiming he wanted to discuss work matters. Within minutes, Spletstoser said, Hyten had pinned her against him and begun “grinding on me hard, like he wants to take my clothes off and have sex . . . and then I realize, he’s ejaculating.”

Those episodes are a sampling of the predatory encounters Spletstoser said she experienced with Hyten. But for senators, the challenge is determining whether they are true.

“I’m trying to determine what the facts are, and that’s very much in contention,” said Sen. Richard Blumenthal (D-Conn.), who has said he finds Spletstoser to be credible. “The factual differences are very stark.”

If Spletstoser’s account is correct, it would mean Hyten committed a crime, but if she is lying, as an active-duty service member, she will have committed a crime for which she could be court-
martialed.

Spletstoser said that she initially kept quiet because she could not figure out “how do you report that on a four-star” without the risk that her life would be “wrecked on a certain level” — and that she remained silent after leaving Hyten’s command because she assumed he was on his way to retirement and her replacement was a man. She decided to tell her story only after Hyten was nominated, she said, “because he’s going to be in for another four years and he could do this to somebody else.”

But according to a former senior Air Force official privy to the investigation’s findings, the testimony of other witnesses directly contradicts Spletstoser’s accusations. The official said that sometimes, Spletstoser also contradicted herself, though she disputes that claim.

Her timing has also raised questions about whether she made up the allegations to retaliate against Hyten, for forcing her to resign from his staff after an inquiry determined that she had created a “toxic work environment” and questioning her mental state. That report was delivered weeks after the alleged December 2017 encounter, which Hyten says never happened.

Spletstoser’s service records, which she provided to The Washington Post, indicate that she had routinely received accolades from her commanders before that point. Hyten wrote in late 2017 that she was in the “top 1%” of all the people in her rank that “I have seen in my 36 years of service,” noting that she was “ready today” to be promoted to brigadier general. The authenticity of the documents could not be verified.

Sworn statements, provided by Spletstoser, from the inquiry into her professional conduct that concluded in early 2018 indicated that while some in the command took offense at her “negative behavior,” they also blamed Hyten for giving her “the highest of top-cover.”

In the interview, Spletstoser acknowledged that she was tough, foulmouthed and often brusque — traits that she attributes to her Army background and the fact that part of her job was to “clean house” in her group. But she said that after Hyten’s management style was questioned, she believes he attempted to “destroy me and my life, my career, everything” to protect his reputation.

Those are just some of the competing claims that fell to military investigators to sort out in their 1,400-page report, which reflects interviews with 53 people in three countries and 13 states, and thousands of emails. The inquiry “determined there was insufficient evidence to support any finding of misconduct against General Hyten,” according to Col. DeDe Halfhill, a Defense Department spokeswoman. Inhofe has described the report, which has not yet been made public, as “very thorough.”

Yet other senators question whether an investigation that was ultimately delivered to one of Hyten’s four-star peers was truly impartial, pointing to what they see as anomalies in how the case was handled.

“The military has a clear process. My concern with this case is that they didn’t follow their process,” said Sen. Tammy Duckworth (D-Ill.), who noted that Hyten had not been subjected to certain basic protocols for accused parties.

“They didn’t suspend his clearance, they didn’t remove him temporarily from his position,” Duckworth said, adding that Spletstoser only got to review a redacted copy of the investigative report less than a week ago. “If Senator Inhofe is going to have this vote now, then I’m going to have to vote from the perspective of, the process was not truly followed, so how do I know and how can I fully trust the completeness of the investigation?”

The 27-member Armed Services Committee has devoted an uncommon level of attention to examining the merits of Splet­stoser’s case and the official probe of it, convening at least four times behind closed doors to let members quiz military personnel about their investigation and pore over the evidence they reviewed, as well as hear out Splet­stoser and Hyten. Both spoke to the panel last week for about three hours each in separate sessions.

Democrats and Republicans alike have spoken highly about the way panel leaders have approached the case — even if they are unsure that the process they have divined can serve as a model for reviewing similar claims.

“The committee’s doing the right thing by doing this respectfully, and they’re really going into every detail and covering the issue the way it should be covered,” said Sen. David Perdue (R-Ga.), a member of the panel. “One of the issues we have in America is innocent until proven guilty. On the other hand, we’ve got this sexual assault issue, and it’s struck a nerve and is something we’ve got to wrestle with as a society . . . it’s hard to generalize about that right now.”

“In the context of criminal law, conviction occurs when there is proof beyond reasonable doubt. But what we have here is a promotion — nobody is entitled to be promoted,” Blumenthal said. “So it has to be a different standard, but I don’t think anyone has articulated it.”

The case also presents another challenge to lawmakers: determining whether the military’s system for reviewing sexual assault and rape cases can provide justice for victims.

“There is a continuing issue of sexual assault in the military, and the work that has been done — and there’s been a lot of work done in the Senate — still has not addressed the core problem,” said Shaheen, who supports efforts led by Sen. Kirsten Gillibrand (D-N.Y.) to take such cases out of the chain of command. “I hope there will be a renewed effort to look at the issue broadly again, because clearly what we have been doing has not been ­working.”

Spletstoser said the military system is designed “to protect junior people from junior people,” but falls apart when the accused perpetrator is so high-ranking he has no apparent boss.

Spletstoser said she ultimately came forward because if Hyten “is promoted to vice chairman, it tells every general officer that they are above the law” and victims “that if you are sexually assaulted, by your superior officer, as long as he does it behind closed doors, not only will your perpetrator not be prosecuted in a court of law, but he may just end up getting promoted to an even higher position,” according to a prepared statement for her closed-door testimony.

“I beg of you not to let this happen,” she said.