AMNA NAWAZ: Beijing said today that the United States, the United Kingdom, and Australia had embarked on a - - quote -- "dangerous path" after those three countries announced a historic submarine agreement yesterday in San Diego.

It's known as AUKUS, for Australia, U.K., and U.S. Nick Schifrin is back with this look at how it will extend one of the most important American weapons systems into waters that China claims as its own.

NICK SCHIFRIN: Military officials call it one of their crown jewels, the nuclear-powered attack submarine, with technology so sensitive, it hasn't been shared with any ally in 65 years, until now.

JOE BIDEN, President of the United States: AUKUS has one overriding objective, to enhance the stability in Indo-Pacific amid rapidly shifting global dynamics.

NICK SCHIFRIN: President Biden made the announcement yesterday, alongside British Prime Minister Rishi Sunak and Australian Prime Minister Anthony Albanese.

JOE BIDEN: One of the vessels you see behind me is a Virginia class nuclear-powered submarine, the USS Missouri.

Top-of-the-line submarines are the vanguard of U.S. naval power.

NICK SCHIFRIN: As we saw for ourselves late last year aboard the same Virginia class USS Missouri.

Navy Commander Carlos Martinez walked me on board.

It can stay underwater longer and travel farther than conventionally powered submarines.

The crew shows how they get a torpedo ready to launch.

Besides torpedoes that can attack ships, these submarines conduct surveillance and can carry cruise missiles to attack targets on land.

It's the one system experts agree is the most difficult for China to detect and can sail through what for China are the most sensitive waters.

CMDR.

CARLOS MARTINEZ, U.S. Navy: If the operational commander tells me, as a ship, that he wants me to go to a certain area via a certain route that's international waters, then that's certainly within our right to do so.

NICK SCHIFRIN: Does that include the Taiwan Strait?

CMDR.

CARLOS MARTINEZ: The international waters of the Taiwan Strait are available for navigation.

NICK SCHIFRIN: The deal with Australia, the U.K. and the U.S. develops in stages.

This year, Australian sailors will embark with American and British sailors.

As early as 2027, one U.K. Astute class submarine and up to four U.S. Virginia class submarines will rotate through a base in Western Australia.

Beginning in the early 2030s, the U.S. will sell Australia as many as five Virginia class submarines.

Meanwhile, Australia and the U.K. will both build a new submarine, called the SSN-AUKUS, ready in the U.K. by the late 2030s and in Australia by the early 2040s.

It's designed to complicate China's military plans, as Beijing tests more missiles than the rest of the world combined and has launched one of the fastest military modernizations in history.

Richard Marles is Australia's defense minister.

RICHARD MARLES, Australian Defense Minister: We are witnessing the biggest conventional military buildup that we have seen since the end of the Second World War, and we need to respond to this.

A failure to do so would see us be condemned by history.

NICK SCHIFRIN: The agreement IS part of the Biden administration's The agreement is part of the Biden administration's plans to confront China by strengthening relations with allies, especially in Asia.

Last week, Chinese President Xi Jinping for the first time accused the U.S. by name of trying to contain China.

To discuss AUKUS and the American drone forced down by Russian jets over the Black Sea, we turn to Mara Karlin, who is performing the duties of deputy undersecretary of defense for policy.

Mara Karlin, welcome back to the "NewsHour."

Thanks very much.

MARA KARLIN, Performing the Duties of U.S. Deputy Undersecretary of Defense for Policy: Thanks so much for having me tonight, Nick.

NICK SCHIFRIN: What consequences will Russia face for helping down a U.S. drone over the Black Sea?

MARA KARLIN: You know, Nick, this was a routine operation that the MQ-9, an uncrewed aircraft, was performing.

And it was doing it in international airspace.

And what we saw by the Russians was unprofessional, it was incompetent, and it was unsafe.

So our colleagues from the State Department are engaging the Russian government right now.

But it really is quite unfortunate to see them take such a -- such steps.

NICK SCHIFRIN: Unfortunate, but will there be a direct consequence?

MARA KARLIN: Our colleagues at the State Department will speak with them about what happened.

But I just want to underscore it's international airspace.

We all know how to operate in safe, competent, professional ways.

And that is not what we saw from the Russians.

NICK SCHIFRIN: Let's turn to AUKUS.

You said that this agreement is not aimed at any one country.

But does the U.S., Australia and U.K. independently having nuclear-powered attack submarines complicate Beijing's plans if it were to decide to go to war?

MARA KARLIN: Nick, indeed, it is not about any one country.

It's about stability and security in the Indo-Pacific.

It's also about delivering deterrence at all four phases, and really what... NICK SCHIFRIN: All four phases of the agreement.

MARA KARLIN: All four -- at all four phases of the agreement.

Having three allies, three very close allies knitted together with this tremendous undersea capability really is going to be important for ensuring that this region, the Indo-Pacific region, can maintain its security, stability and its prosperity going forward.

NICK SCHIFRIN: Is China more deterred by Australia having a nuclear-powered attack submarine than it is by the United States having yet another nuclear-powered attack submarine?

MARA KARLIN: The United States is lucky to have a tremendous network of allies and partners and tremendous undersea capabilities.

Having three allies with these capabilities, strengthening our defense industrial bases, does show that we're willing to work together in any number of challenges.

And, look, the U.K., Australia have stood by the United States.

Together, we have dealt with no shortage of challenges around the globe.

And now we are all especially focused on the Indo-Pacific.

NICK SCHIFRIN: You announced today that Australia will purchase both new and older Virginia class submarines, says the plan.

Will the U.S. shipbuilding industry have to build extra submarines for Australia, or will Australia got to cut the line and get a sub that was supposed to go to the U.S. Navy?

MARA KARLIN: So, Australia will be getting a mix.

They will be purchasing a mix of submarines that are in service, so submarines that the U.S. Navy has been using, and then newer submarines.

And those, we will deliver.

And the first one will be in hand in less than a decade, which is actually really fast, given just the significance of this -- of this capability.

Our submarine industrial base has really needed a lot of investment.

The Biden administration has pushed for that investment, and Congress has delivered.

In fact, the defense budget, as you know, was unveiled yesterday.

There's $4.6 billion in increasing our production and our maintenance of our submarine industrial base.

So that's really important.

Australia will also be contributing a proportional amount to that submarine industrial base.

So we're going to work together with the Australians to make sure, as we have throughout the last 18 months of developing this massive plan that the heads of state had devised, in ensuring that they are getting what they need, and we are doing so as well.

NICK SCHIFRIN: But will Australia get to cut the line?

MARA KARLIN: It's really not an issue of cutting the line.

It's really an issue of making sure that we can increase our maintenance.

Right now, we have a lot more submarines that are -- we have got a maintenance backlog, if you will.

If we can increase that, that will be really important to make sure our submarines are ready and out and about and to be able to increase that production.

Look, we have put in, thanks to the Congress, extra funding in that industrial base.

That early investment is going to have an outsized effect.

And I think we are increasingly going to see that we have the facilities and that we have the talent that we need to make all of this a reality.

NICK SCHIFRIN: You have acknowledged this.

There has been maintenance issues.

There have been huge production issues.

The Congress has funded two Virginia class submarines per year, but there's only 1.2, on average, being produced.

And you cited the $4.6 billion number, but the Republicans on the Hill say that's not enough.

Take a listen to this statement from Roger Wicker.

He is the top Republican on the Senate Armed Services Committee: "The Biden administration has never asked Congress for the type of generational investment of resources, authorities and political capital in our submarine industrial base to meet our own Navy's submarine requirements, let alone additional requirements."

And this is somebody who is in favor of AUKUS and what you have been doing.

What's your response to that?

MARA KARLIN: Well, first of all, I have been pleased to see the tremendous bipartisan support for AUKUS.

It really is a generational leap in this alliance.

It's a game-changer, and a big play.

In terms of the comments on the need to invest in the submarine industrial base, we're working very closely with Congress to be able to max the investment that the industrial base can absorb.

We're also studying really hard to see what effect the investments are having as we go forward.

I think... NICK SCHIFRIN: And the effect that AUKUS could have, do you believe that it will tax the industrial base further?

MARA KARLIN: I believe that AUKUS will help lift up the submarine industrial base for us, for the United Kingdom, and for Australia.

NICK SCHIFRIN: Because Australia is going to invest into the American industrial base, just like the U.S. is investing in itself?

MARA KARLIN: They are indeed.

But I would underscore just the increasing recognition that we, as a country, have in our spectacular undersea capabilities and the need to ensure we can maintain that comparative advantage.

NICK SCHIFRIN: Mara Karlin, thank you very much.

MARA KARLIN: Thanks for having me.