By David Brunnstrom and Eric Beech

WASHINGTON (Reuters) -U.S. Chief of Naval Operations Admiral Michael Gilday said on Monday the United States did not underestimate the difficulties ahead in realizing a three-nation project to supply Australia with nuclear-powered submarines and still did not know exactly where the initial batch of vessels would come from.

U.S. Indo-Pacific Coordinator Kurt Campbell told the same Washington event there was “every indication” the AUKUS project would be sustained politically in the United States and Australia, and that Washington was talking to a variety of countries about taking part in its so-called second pillar.

The multi-stage AUKUS project announced in March is planned to culminate in the late 2030s and early 2040s with British and Australian production and operation of a new submarine class – SSN-AUKUS – and include “cutting edge” U.S. technologies.

Before that, in the early 2030s, the United States is supposed to sell Australia three U.S. Virginia class nuclear-powered submarines, with an option for Australia to buy two more.

Big questions remain, however, not least over strict U.S. curbs on the extensive technology sharing needed and about how long it will take to deliver the Virginia-class submarines, given limited U.S. production capacity to meet its own needs, even as the perceived threat posed by China that inspired the project mounts.

Asked at Washington’s Center for Strategic and International Studies think tank about the Virginia-class submarines, Gilday said it was still “too early to give you an answer on precisely where those submarines will come from, whether that’s excess capacity or whether that comes out of U.S. inventory.”

“We’re trying to put the industrial base in a position where they can increase their productivity,” he said, adding that the priority was still production of Columbia-class submarines for the U.S. Navy.

Gilday said the U.S. was “aspirational at this point” on reaching a production goal of two Virginia Class vessels a year, adding: “I can’t give you a specific date when we expect to close on two, but we’re headed in the right direction.”

Gilday said he saw “huge potential” for other countries to become involved in selected parts of the second pillar of AUKUS, which involves hypersonics and other weaponry that can be deployed more quickly.

This would depend on their ability to “bring technology to bear that is going to make a difference, and that we have high trust and confidence that we can share that information back and forth,” he said.

Campbell said areas for involvement of “some allies and partners” in “either direct or niche areas” of pillar two could include hypersonics, cybersecurity, and anti-submarine warfare.

(Reporting by David Brunnstrom, Eric Beech, Michael Martina; additonla reporting by Mike Stone; Editing by Leslie Adler and Deepa Babington)

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