SALT LAKE CITY — Utah became the only state to allow firing squads for executions Monday when Gov. Gary Herbert signed a law approving the controversial method’s use when no lethal-injection drugs are available.

Herbert has said he finds the firing squad “a little bit gruesome,” but 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, when a jury makes the decision and a judge signs a death warrant, enforcing that lawful decision is the obligation of the executive branch.”

The measure’s approval is the latest illustration of some states’ frustration over bungled executions and difficulty obtaining the drugs. Utah is one of several states seeking new forms of capital punishment after a botched Oklahoma lethal injection last year.

States have struggled to keep up their drug inventories as European manufacturers opposed to capital punishment refuse to sell the components of lethal injections to U.S. prisons.

The bill’s sponsor, Republican Rep. Paul Ray, argued that a team of trained marksmen is faster and more decent than the drawn-out deaths involved when lethal injections go awry – or even if they go as planned.

Though Utah’s next execution is probably a few years away, Ray said wants to settle on a backup method now.