The United States, where the death penalty is still carried out, on Wednesday steered clear of a storm of global protest triggered by Indonesia's execution of seven foreign drug traffickers.

The seven -- two from Australia, one from Brazil and four from Africa -- were shot along with one Indonesian, despite strident foreign appeals and pleas from family members.

PHOTO GALLERY: A look back: Indonesia executions

"We don't have much to say on this, other than we're aware that they have executed eight (sic) foreign citizens convicted of drug trafficking," State Department acting spokeswoman Marie Harf said.

"As we've said, none of these eight were Americans."

She spoke as the US Supreme Court heard arguments Wednesday about lethal injections, after states began using alternative drugs -- believed by some to cause pain and suffering -- to carry out the executions.

A total of 18 out of 50 US states and the US capital Washington have abolished the death penalty, and the number of executions has fallen in recent years since the capital punishment was reinstated in 1976.

Of the 1,407 executions performed in the US since 1976, 13 have taken place so far this year.

READ: Indonesian executions spark international anger

Australia has withdrawn its ambassador to Jakarta in protest at the execution of their nationals, and the European Union has expressed dismay.

In Massachusetts meanwhile, defense lawyers are trying to save Boston bomber Dzhokhar Tsarnaev from a federal death sentence after he was convicted of carrying out the 2013 Boston bombings in which three people were killed.

US attorneys have argued that the 21-year-old of Chechen descent deserves to die for one of the bloodiest attacks on US soil since the 2001 9/11 attacks.

READ: Decision to execute foreigners sets Indonesia apart