SALT LAKE CITY — Utah became the only state to allow firing squads for executions when Gov. Gary Herbert signed a law approving the method for use when no lethal injection drugs are available, even though he has called it “a little bit gruesome.”

The Republican governor has said Utah is a capital punishment state and needs a backup execution method in case a shortage of the drugs persists.

“We regret anyone ever commits the heinous crime of aggravated murder to merit the death penalty, and we prefer to use our primary method of lethal injection when such a sentence is issued,” Herbert spokesman Marty Carpenter said. However, enforcing death sentences is “the obligation of the executive branch.”

The governor’s office noted that other states allow execution methods other than lethal injection. In Washington state, inmates can request hanging. In New Hampshire, hangings are fallback if lethal injections can’t be given. And an Oklahoma law would allow the state to use firing squads if lethal injections and electrocutions are ever declared unconstitutional.

Utah’s new approval of firing squads carries no such legal caveat and represents the latest example of frustration over botched executions and the difficulty of obtaining lethal injection drugs as manufacturers opposed to capital punishment have made them off-limits to prisons.