Washington: A US Navy attack submarine struck an object while submerged in international waters in the South China Sea, officials have said.
They said on Thursday that there were no life-threatening injuries and the submarine was still fully operational.
In a brief statement providing few details of an incident that happened five days ago, US Pacific Fleet said the USS Connecticut remained in a "safe and stable condition".
The Seawolf-class submarine's nuclear propulsion plant was not affected, it added.
"The extent of damage to the remainder of the submarine is being assessed," the statement said, adding that the incident will be investigated.
The statement did not specify the location of the incident, but two Navy officials, speaking on condition of anonymity to discuss details not announced publicly, said it happened in the South China Sea while the Connecticut was conducting routine operations.
The officials said the sub then headed towards port at Guam. They said the incident was not announced before Thursday in order to maintain operational security.
They said it was not yet clear what object the sub had struck but that it was not another submarine. One official said it could have been a sunken vessel, a sunken container or other uncharted object.
Two sailors aboard the Connecticut sustained moderate injuries and about nine others had minor injuries like scrapes and bruises, the officials said. All were treated aboard the sub.