Lawyers say Abde Wale Abdul Kadhir Muse is "injured and terrified"
A Somali teenager captured by the US during the rescue of an American sea captain from pirates has appeared in a federal court in New York.
The judge briefly closed the trial to the public until he had clarified whether Abde Wale Abdul Kadhir Muse was a juvenile as his mother claimed.
The judge re-opened the trial, saying the suspect would be tried as an adult.
The teenager will be the first person to face piracy charges in the US in over a century, US media reports say.
He cried at the hearing on Tuesday, Associated Press news agency reported.
Earlier, his mother appealed to US President Barack Obama to free him.
Adar Abdurahman Hassan told the BBC her son was innocent and just 16 years old.
In other developments:
• Somali pirates have freed a chemical tanker and its crew of 23 Filipinos after holding them for five months
• The Philippine government has banned its sailors from working on ships that might travel through the Gulf of Aden, where the Somali pirates operate
The teenager is accused of being a member of the pirate gang which boarded the Maersk Alabama container ship on 8 April and took Capt Richard Phillips hostage in a lifeboat.
The stand-off ended on the fifth day when US Navy marksmen killed three of the pirates while Abde Wale Abdul Kadhir Muse was aboard a US warship allegedly demanding a ransom.
The teenage suspect arrived in the US late on Monday, under heavy guard.
On Monday his mother said she wanted to be present in court if the case went ahead.
She said her son had been missing for two weeks prior to the hijacking and she only realised he had been implicated when she heard his name in a radio report.
She told the BBC's Somali service: "I am requesting the American government, I am requesting President Obama to release my child. He has got nothing to do with the pirates' crime.
"He is a minor. He is under-age and he has been used for this crime. I also request from the US, if they choose to put him on trial, I want them to invite me there."
On Sunday, the internationally-recognised but fragile Somali government said captured pirates could face the death penalty.
But the Horn of Africa nation has been without an effective administration since 1991, fuelling the lawlessness which has allowed piracy to thrive.
Shipping companies last year handed over about $80m (£54m) in ransom payments to the gangs.