OKLAHOMA CITY — As the drugs become increasing difficult to obtain, Oklahoma will stop using lethal injection and plans to become the first to execute inmates using the untried method of inert gases, officials announced Wednesday.

The state plans to implement a 2015 law that allows executions using nitrogen hypoxia if lethal injection is declared unconstitutional or the drugs needed to put inmates to death are unavailable, Oklahoma Attorney General Mike Hunter said.

Hunter said opponents of capital punishment are “waging a guerilla war” against the death penalty. That’s made it impossible for many states, including Oklahoma, to obtain the necessary drugs to safely continue with lethal injection.

Hunter said the state plans to abandon its current lethal injection procedure, which relies on a three-drug cocktail — Midazolam, vecuronium bromide and potassium chloride — inserted into an IV.

“As state leaders, it is our duty to find an effective and humane manner that satisfies both the Constitution and the court system,” Hunter said. “We can no longer sit on the sidelines and wait to find drugs. Using (inert gases) will be effective, simple to administer, easy to obtain and requires no complex medical procedures.”

No Oklahoma inmate has been executed since 2015 following several mishaps. A bungled procedure in 2014 left an inmate writhing on the gurney. In 2015, an execution was reportedly carried out with the wrong drug, and a second halted after a similar issue was discovered.

Meanwhile, 17 death row inmates have exhausted all appeals and are awaiting execution dates, Hunter said.

Oklahoma officials said they didn’t know when executions would resume but hope to draft the new gas protocols within the next 120 days. Executions would resume as soon as possible after that. State law also allows officials to opt for firing squads or the electric chair in executions.

Joe M. Allbaugh, Oklahoma Department of Corrections director, said he’s “been in the mad hunt for drugs” and in conversations with “seedy individuals who had access to drugs” since he started in January 2016.

“I was calling all around the world to the back streets of the Indian subcontinent to procure drugs,” he said.

As demand outpaces supply, the drugs are more expensive to obtain, he said. Nitrogen is less expensive.

In addition, Allbaugh said inmates have stopped hydrating days and weeks leading up to executions, which makes it more difficult for medical personnel to insert needles.

Hunter said well-documented medical evidence shows that using nitrogen or other gases like argon and helium is “the safest, the best and most effective method available.”

Execution officials said the chemical element would likely be administered using a specially designed gas mask. Individuals who are exposed to excessive amounts of the inert gases have reported experiencing fatigue, dizziness, headache, loss of breath and eventually consciousness, Hunter said.

“It is a common procedure in states and in countries that allow for assisted suicide,” Hunter said.

In a statement, Dale Baich, an assistant federal public defender, who is representing Oklahoma death row prisoners in an execution method lawsuit, said the process must proceed with “due diligence and caution.”

“This method has never been used before and is experimental,” Baich said. “Oklahoma is once again asking us to trust it as officials ‘learn on the job,’ through a new execution procedure and method. How can we trust Oklahoma to get this right when the state’s recent history reveals a culture of carelessness and mistakes in executions?”

Don Heath, chair of the Oklahoma Coalition to Abolish the Death Penalty, said he was “a little surprised” by the announcement. He said he’d heard the state was going to stick with lethal injection in part because the new method is untested and going to require a lot of appeals.

“It’s hard to say it’s a good thing, killing people a different way,” he said. “I think it’s a good thing in that it will delay the process further. It will be some time, I think, before an execution can be scheduled.”

Janelle Stecklein covers the Oklahoma Statehouse for CNHI’s newspapers and websites. Reach her at jstecklein@cnhi.com.