TAPPER: The captain of the USS Theodore Roosevelt, Captain Brett Crozier, was relieved at his command on Thursday after he wrote a memo that expressed his dire concerns about the more than 100 infected sailors in a coronavirus outbreak on his ship and whether or not those individuals would spread the virus to the thousands of sailors also on the ship.

I want you to take a look at this video of Captain Crozier leaving the ship to cheers from his fellow sailors.

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UNIDENTIFIED NAVY SAILORS: Captain Crozier! Captain Crozier! Captain Crozier!

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TAPPER: So, Secretary Esper, can you explain to those sailors cheering, "Captain Crozier, Captain Crozier," why exactly he was relieved of his command?

ESPER: Well, Jake, first of all, first and foremost, we need to take care of the sailors on the ship. We need to ensure their well-being and get that ship back out to sea as soon as possible.

I'm pleased to report, right now, over half of the ship has been tested. Only 155 sailors have come up positive. Those are all mild and moderate. There have been no hospitalizations whatsoever.

So, the -- the crew is being taken care of out there.

With regard to the relief of Captain Crozier, I think acting Secretary Modly made a very tough decision, a decision that I support. It was based on his view that he had lost faith and confidence in the captain, based on his actions. It was supported by Navy leadership.

And I think it's -- it's just another example how we hold leaders accountable for their actions.

TAPPER: Shouldn't there have been at least an investigation before he was relieved of command? I mean, the captains of the USS John McCain and the USS Fitzgerald, who were captains when sailors died at sea, they at least had investigations before they were relieved of their commands.

Captain Crozier was trying to save lives, and he wasn't even afforded the benefit of an investigation.

ESPER: Well, there is an investigation ongoing.

But, at this point in time, the -- Secretary Modly did not have faith and confidence that he could continue in his role as captain of the ship. That is not unheard of. The -- all the services at time relieve commanders without the benefit of an investigation up front because they have lost confidence in them.

It's certainly not unique to the Navy. The Navy has a culture of swiftly and decisively removing captains if they lose confidence in them.

TAPPER: You know there are a number of noted high-ranking formal -- former officials, like Admiral Mullen, who was former chair of the Joint Chiefs, Admirals Stavridis, who is former NATO supreme allied commander, both of whom have said they did not think it was appropriate for Crozier to have been relieved of duty so quickly, without an investigation, and that it would undermine morale.

On the other hand, of course, you had President Trump, who said that he thought it was not appropriate for Crozier to even write the letter. Take a listen.

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TRUMP: I thought it was terrible, what he did, to write a letter?

I mean, this isn't a class on literature. He shouldn't be talking that way in a letter. He could call and ask and suggest.

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TAPPER: He wrote a letter to try to save the lives of his sailors. Do you think that's terrible that he did that?

ESPER: Well, Jake, I can't get too much into the facts of the matter, because there is an investigation ongoing. This could ultimately come to my desk.

I think Secretary Modly laid out the -- very reasonably, very deliberately the reasons why. And I think, when all those facts come to bear, we will have a chance to understand why Secretary Modly did what he did.

TAPPER: Acting Navy Secretary Modly reportedly told a colleague on Wednesday -- quote -- "Breaking news: Trump wants him fired."

Did -- ultimately, this decision, was it made by President Trump?

ESPER: This was Secretary Modly's decision. He briefed me about it. And I got -- I took the advice of the CNO and General Milley with regard to it. And I told him I would support his decision.

TAPPER: I want to ask you about the sailors, because you mentioned what was going on with them.

A Pentagon spokesperson Friday said the goal was to have a total of 2,700 sailors off the ship by Friday evening. As of yesterday afternoon, only 1,548 sailors had been moved to shore, more than 1,000 away from your goal.

What's the latest? And why has the Navy failed to reach the goal? When will everyone be off the ship?

ESPER: Well, the Navy is -- is working that very carefully, very closely.

The new commander will be out there, should be out there very soon. There is not a need necessarily to remove every sailor from the ship. You actually cannot do that, because there's nuclear reactors to be run. You have very sensitive equipment. You have weapons on board that ship, so you cannot completely evacuate the ship.

So it's how you manage the crew to make sure you're protecting them, segregating, treating those who need treated, while, at the same time, maintaining the readiness of the ship, in case it's called upon to get to sea quickly.

TAPPER: Doesn't the fact that the Navy hasn't even gotten all the sailors off the ship that they said they were going to get off by Friday night underline Captain Crozier's concern that the Navy is not taking this seriously enough, with the urgency it deserves?

ESPER: I think that's a completely false narrative, Jake.

The Navy's been on top of this now for several days, when it first came down that we had the first cases aboard the Teddy Roosevelt. The CNO, the chain -- the entire military chain of command, Secretary Modly himself have been involved, moving supplies, testing kits, providing support to the sailors from Guam, at Guam.

They -- they were all in terms of providing support to this crew, this ship, as it arrived in port. So, I -- I disagree with that assumption.

TAPPER: I want to...

ESPER: I have a lot of faith and confidence in the Navy leadership.