Happy Tuesday and welcome to Overnight Defense. I'm Ellen Mitchell, and here's your nightly guide to the latest developments at the Pentagon, on Capitol Hill and beyond. CLICK HERE to subscribe to the newsletter.

THE TOPLINE: Acting Navy Secretary Thomas Modly resigned on Tuesday after fanning the flames of a controversy over a coronavirus outbreak on board an aircraft carrier.

Defense Secretary Mark Esper Mark EsperTop admiral: 'No condition' where US should conduct nuclear test 'at this time' Overnight Defense: Trump hosts Israel, UAE, Bahrain for historic signing l Air Force reveals it secretly built and flew new fighter jet l Coronavirus creates delay in Pentagon research for alternative to 'forever chemicals' Oldest living US World War II veteran turns 111 MORE confirmed on Tuesday that he had accepted Modly's resignation that morning.

"He resigned on his own accord, putting the Navy and the Sailors above self so that the U.S.S. Theodore Roosevelt, and the Navy as an institution, can move forward," Esper said in a statement. "I have the deepest respect for anyone who serves our country, and who places the greater good above all else. Secretary Modly did that today, and I wish him all the best."

The lead up: The resignation comes a day after transcripts and audio of an inflammatory speech, in which Modly defended his decision to fire Capt. Brett Crozier as commander of the USS Theodore Roosevelt, leaked to the media.

Modly relieved Crozier of his command of the Roosevelt last week after a letter the captain wrote pleading for help with coronavirus outbreak on the ship leaked in the media.

In the speech aboard the Roosevelt, Modly said that if Crozier didn't think the letter would leak, he was "too naive or too stupid to be a commanding officer of a ship like this."

Alternatively, Modly said, if Crozier leaked the letter on purpose, that would be a "serious violation" of the Uniform Code of Military Justice.

He also called Crozier's action a "betrayal" and warned sailors that there is "no situation" in which they should go to the media, alleging "the media has an agenda" that "depends on which side of the political aisle they sit."

A delayed apology: Modly at first said Monday afternoon he stands by "every word," but by Monday night was apologizing.

"Let me be clear: I do not think Captain Brett Crozier is naive or stupid," Modly said in a statement. "I apologize for any confusion this choice of words may have caused."

Lawmakers called for removal: The speech led to a number of calls for his removal from Democrats including Rep. Elaine Luria Elaine Goodman LuriaUS Chamber of Commerce set to endorse 23 House freshman Democrats House panel votes against curtailing Insurrection Act powers after heated debate Republican Scott Taylor wins Virginia primary, to face Elaine Luria in rematch MORE (D-Va.), a Navy veteran; Sen. Tammy Duckworth Ladda (Tammy) Tammy DuckworthMcConnell focuses on confirming judicial nominees with COVID-19 talks stalled Biden courts veterans amid fallout from Trump military controversies John Fogerty: 'Confounding' that Trump campaign played 'Fortunate Son' at rally MORE (D-Ill.) a combat veteran and member of the Senate Armed Services Committee; House Armed Services Committee Chairman Adam Smith David (Adam) Adam SmithWhen 'Buy American' and common sense collide Overnight Defense: Marine Corps brushes off criticism of Marines' appearance in GOP convention video | US troops injured in collision with Russian vehicle in Syria | Dems ask for probe of Vindman retaliation allegations Democrats press Pentagon watchdog to probe allegations of retaliation against Vindman brothers MORE (D-Wash.); and Speaker Nancy Pelosi Nancy PelosiMcConnell focuses on confirming judicial nominees with COVID-19 talks stalled Overnight Defense: Top admiral says 'no condition' where US should conduct nuclear test 'at this time' | Intelligence chief says Congress will get some in-person election security briefings Pelosi must go — the House is in dire need of new leadership MORE (D-Calif.).

"I can reach no other conclusion than this situation has overwhelmed [Modly's] ability to act professionally when acting professionally was what was needed most. We do, and we should, expect more from those in charge of our Armed Forces, and Acting Secretary Modly must resign immediately," Duckworth, a combat veteran and member of the Senate Armed Services Committee, said in a statement Tuesday.

The replacement: Esper said is appointing current Army Undersecretary Jim McPherson as acting Navy Secretary.

"Jim is a retired Admiral with a distinguished 26 year naval career, serving ashore, afloat, and overseas during his time in uniform. I know Jim McPherson well. He is a smart, capable, and professional leader who will restore confidence and stability in the Navy during these challenging times. Jim will serve as acting Secretary of the Navy until a permanent Navy Secretary is confirmed."

In other coronavirus news...

House panel wants docs on aircraft carrier's outbreak: A House subcommittee chairman is asking the Pentagon for documents related to the coronavirus outbreak aboard a U.S. aircraft carrier.

Rep. Stephen Lynch Stephen Francis LynchOvernight Defense: Dems divided on length of stopgap spending measure | Afghan envoy agrees to testify before House panel | Trump leans into foreign policy in campaign's final stretch Afghan envoy agrees to testify before House panel after subpoena threat Overnight Defense: Trump's battle with Pentagon poses risks in November | Lawmakers launch Fort Hood probe | Military members can't opt out of tax deferral MORE (D-Mass.), chairman of the House Oversight and Reform National Security Subcommittee, is requesting the information after Capt. Brett Crozier was fired as commander of the USS Theodore Roosevelt after a letter he wrote warning about the outbreak on the ship was leaked to the media.

"Although it seems Capt. Crozier may have operated outside his chain of command, it appears that he did what he thought was best for the health and safety of his crew and the readiness of his ship to successfully carry-out their mission," Lynch wrote in a letter Tuesday to Defense Secretary Mark Esper. "I certainly do not want his removal to have a chilling effect on military leaders who have been entrusted to protect the men and women under their command in this challenging operational environment."

Lynch specifically requested documents or communications related to the Roosevelt's early March port visit of Danang, Vietnam, and the subsequent coronavirus outbreak to or from several top officials, including Esper, Modly, Crozier, Joint Chiefs of Staff Chairman Gen. Mark Milley, Chief of Naval Operations Adm. Michael Gilday and other top naval officers.

Lynch asked for the documents by April 17.

Trump replaces Pentagon IG, removes him from coronavirus panel: Trump has replaced the Pentagon's top watchdog a week after he was named to lead a committee charged with overseeing the $2 trillion coronavirus relief package.

Glenn Fine, who has served as acting Pentagon inspector general since 2016, will go back to being the principal deputy inspector general and will no longer lead the coronavirus relief oversight panel, his office said Tuesday.

"Yesterday, the president nominated Mr. Jason Abend for the position of DoD Inspector General," Dwrena Allen, spokeswoman at the Department of Defense Office of the Inspector General, said in an email. "The same day, the president also designated Mr. Sean W. O'Donnell, who is the Environmental Protection Agency Inspector General (EPA IG), to serve as the Acting DoD IG in addition to his current duties at the EPA."

The EPA IG's office similarly told The Hill that O'Donnell "is filling both roles for now" and that "no changes are expected at the EPA OIG."

Fine "remains focused and committed to the important mission of the DoD OIG," Allen added.

The move also means that Fine is no longer on the Pandemic Response Accountability Committee, she said.

The panel of inspectors general was created by the $2.2 trillion stimulus bill Congress passed last month to audit and investigate implementation of the bill.

Fine was appointed as chairman of the committee last week, a move that won praise across the political spectrum

Comfort crew member tests positive for coronavirus: A crew member aboard the USNS Comfort, which is serving as a temporary hospital while docked in New York harbor, has tested positive for the novel coronavirus, the Navy confirmed to multiple news outlets.

"There is no impact to Comfort's mission, and this will not affect the ability for Comfort to receive patients," the Navy told ABC News, which first reported the development. "The ship is following protocols and taking every precaution to ensure the health and safety of all crewmembers and patients on board."

The crew member had no contact with patients and is in isolation aboard the ship, according to the Navy's statement.

A spokesperson for the Navy was not immediately available for comment when contacted by The Hill on Tuesday.

The USNS Comfort was just designated to treat COVID-19 patients after a request from Gov. Andrew Cuomo Andrew Cuomo44 percent of high earners have considered leaving New York City: poll Media's anti-Trump coronavirus spin has real consequences In defense of Trump's efforts to quell pandemic panic MORE (D).

The ship had initially been set to treat non-coronavirus patients, but Cuomo said there was not a large need for treating uninfected patients.

ON TAP FOR TOMORROW

The Atlantic Council will hold a webinar on "Spheres of influence: Outdated relic or renewed reality?" with Steven Pifer, former deputy assistant secretary of state for European and Eurasian affairs; and former U.S. Ambassador to Ukraine John Herbst, among others, at 2:30 p.m.

ICYMI

-- The Hill: Trump takes heat for firing intel watchdog during pandemic

-- The Hill: House Armed Services chairman expresses confidence in Esper amid aircraft carrier coronavirus crisis

-- The Hill: Army begins testing possible coronavirus vaccines on primates at Fort Detrick

-- The Hill: Schiff calls on DNI Grenell to explain intelligence community changes

-- The Hill: Samantha Power Samantha Jane PowerSupport swells for renaming Edmund Pettus Bridge in Selma to honor John Lewis after his death 'Obamagate' backfires: Documents show Biden, Obama acted properly 'Unmaskings' may be common — and that's the problem MORE: UN covering up Russia's role in Syria bombings

-- The Hill: Navy hospital ship to treat coronavirus patients after outcry

-- The Hill: Opinion: Coronavirus reveals the vulnerable nature of our medical supply chain

-- The Hill: Opinion: Navy Secretary Modly's aircraft carrier speech misfires badly

-- The Hill: Opinion: While the world battles the coronavirus, our adversaries are planning their next attack