Two men have been charged in separate cases with sexually assaulting women on commercial flights bound for Seattle earlier this year, cases prosecutors said Thursday they hope will encourage victims and others to report such attacks.

"Nobody getting on a plane — not a mother, daughter, sister or son, or anyone else — should have to endure what we allege happened in these cases," Seattle U.S. Attorney Annette Hayes said at a news conference. "Planes are not a law-free zone."

The defendants were identified as Babak Rezapour, 41, of Van Nuys, California, and Nicholas Matthew Stevens, 37, of Anchorage, Alaska. Each is in custody and expected to make initial court appearances in their home states in the coming days, prosecutors said.

They face up to two years in prison and could be required to register as a sex offender if convicted.

Court records did not indicate if either had obtained an attorney.

The FBI says it has seen a jump in reports of sexual assault cases aboard airplanes, especially since the #MeToo movement began focusing attention on the topic in the past year. The number of cases it opened rose from 38 in 2014 to 63 last year, according to agency statistics.

Prosecutors said Rezapour repeatedly groped a 21-year-old woman as she slept during a Norwegian Air flight from London last January. Charging documents said the woman took prescription anti-nausea and anti-anxiety medicine and drank a glass of wine. Later in the flight, Rezapour, who was sitting nearby with one empty seat between them, ordered her a second glass; she felt unusually hazy and had trouble staying awake after drinking it.

The victim repeatedly woke up to find Rezapour groping her under her bra, touching her genitals or placing her hand on his exposed penis, which he had concealed under a jacket, the complaint said. She eventually went to the back of the plane, where a flight crew member found her crouched down and crying.

Flight attendants reseated her in the front of the plane, and one crew member questioned Rezapour. Her asked if he could apologize to her, and when asked why he would need to, he said he might have accidently kicked her, the complaint said. Police met the plane upon landing; Rezapour denied having engaged in any unwanted touching.

Tests on the woman's clothing found Rezapour's DNA, authorities said.

Stevens is charged with assaulting a 22-year-old woman on an Alaska Airlines flight from Anchorage in March. Prosecutors said he sat in an aisle seat while she was in a window seat. When he asked if he could move to the middle and put his head on her shoulder, she refused, they said, but he kept asking and eventually she relented and said, "Whatever."

After moving to the middle seat, he began joking about killing people, high-fived her and gave her fist-bumps. Eventually he started grabbing her breasts and thighs, prosecutors said. She removed his hand and told him to stop.

After the plane landed, two other passengers who observed some of his behavior urged her to report him, and she did. An Alaska Airlines manager found Stevens at a gate, and she identified him as the man who assaulted her. He told police they had been touching each other, the complaint said.

The complaints were filed under seal Aug. 22, after months of investigation and review for prosecution. They were made public Thursday following the men's arrests.

The U.S. attorney and Jay Tabb, the special agent in charge of the FBI field office in Seattle, said it's crucial for victims or witnesses to report such cases quickly because passengers don't always sit in their assigned seats, which can make it difficult to identify suspects after the fact.