Admiral Samuel Paparo, commander of US Indo-Pacific Command, also reaffirmed Australia's geographic position as "absolutely essential" to Washington as China expands its influence in the region.
Admiral Paparo told a House Armed Services Committee hearing that HMAS Stirling in Western Australia was on track for the rotational force that will arrive in Perth in a little over a year.
"We could be ready today to operate a rotational submarine squadron out of Australia tomorrow," he said.
"The Australian submariners are performing well on the ships. They're performing well in the schools, extremely well, and in every regard in Pillar I, we're on track.
"We're making strides in Pillar II among these non-traditional systems here. And to have a rotational base in the Indian Ocean is absolutely essential."
Australia has been promised at least three Virginia-class submarines from the US in the early 2030s, before a new fleet of vessels is built for delivery from the 2040s.
A Pentagon review of the AUKUS agreement last year sparked concern Australia might not be sold the boats, as US shipyards come under increasing pressure to keep up production.
But Admiral Paparo said his opinion on the necessity of the security deal was "vindicated" by the report.
Addressing the media in Canberra on Thursday, senior US Space Force officer Lieutenant General Gregory Gagnon warned warfare will extend to space, as China expanded the number of satellites in outer space to about 1400.
"About half of them are remote sensing ... so that they can see Australian forces moving, so that they can see US forces moving," he said.
Lieutenant General Gagnon said he was concerned by the "rapid acceleration" of the Chinese space program.
"They are moving out like a world-class sprinter and they are making gains," he said.
"They have built the weapons to attack us in space. They have practised using those weapons to attack us in space.
"We no longer have the benefit of ignoring that."
