Lee sent a series of tweets at Kishida Tuesday afternoon making vague threats if Alkonis was not released.
"Hand Lt. Alkonis over to U.S. custody immediately," Lee said in one message.
"If you don’t hand him over in the next seven hours, a series of conversations will begin tomorrow to inform Americans of how poorly you’re treating our military personnel—not just Ridge Alkonis, but all 55,000 U.S. forces in Japan," he tweeted later.
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Many Americans view Ridge Alkonis' imprisonment in Japan as unjust.
"You've made your choice," Lee tweeted just minutes after the midnight deadline past. "I hope you're ready for some conversations on the Senate floor that you're not likely to enjoy. This issue isn't going away, and neither am I."
Lee has floated the possibility of blocking a sale of tomahawk missiles to Japan over the incident. He will also demand Alkonis' release on the Senate floor later Wednesday, according to Politico.
Alkonis' wife, Brittany Alkonis, has blasted the Pentagon for "abandoning" her husband overseas. Brittany says her husband suffered a bout of "acute mountain sickness" when driving down from Mt. Fuji, and the medical emergency caused him to lose control of his vehicle.
The resulting crash killed two people, and Alkonis was convicted of negligent driving.
Lt. Ridge Alkonis and a family member. ('Fox News @ Night' screenshot)
"He was convicted of negligent driving resulting in death or injury, but a medical emergency like a heart attack, a stroke, a seizure, that is not a crime in America, and it is also not a crime in Japan…"
"He should not be in jail right now," she told "Fox & Friends Weekend" in January.