Overnight Defense: Trump identifies first soldier remains from North Korea | New cyber strategy lets US go on offense | Army chief downplays talk of 'Fort Trump'
Overnight Defense: Trump marks 9/11 anniversary | Mattis says Assad 'has been warned' on chemical weapons | US identifies first remains of returned Korean war troops
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: President Trump and other Washington leaders on Tuesday marked the 17th anniversary of the terrorist attacks of Sept. 11, 2001, during ceremonies and memorials across the country.
Trump took part in a morning ceremony at the 9/11 memorial in Shanksville, Pa., where United Airlines Flight 93 crash-landed after a group of passengers thwarted a likely attack on the nation's capital. Forty passengers and crew members died as a result of the crash.
The scene: "This field is now a monument to American defiance. This memorial is now a message to the world: 'America will never, ever, submit to tyranny,' " Trump said during a ceremony in Shanksville, Pa.
"We honor their sacrifice by pledging to never flinch in the face of evil and by doing whatever it takes to keep America safe," Trump said.
Trump spoke for roughly 20 minutes, peppering in personal details and stories from those who died or lost loved ones.
The attacks: Nearly 3,000 people were killed on Sept. 11, 2001, when hijackers flew commercial airplanes into the World Trade Center towers, the Pentagon and a field in Shanksville.
At the Pentagon: Defense Secretary James Mattis on Tuesday morning addressed families of 9/11 victims at the Pentagon's Sept. 11 memorial alongside Vice President Mike Pence and Joint Chiefs of Staff Vice Chairman Gen. Paul Selva.
"Though evil visited us on a cloudless Tuesday morning, courage and strength answered amid the fire and smoke in New York City, over a Pennsylvania meadow, and in this very building, as innocent people from 91 countries were murdered on our soil," Mattis said at the observance ceremony.
"We remember that hatred, disguised in false religious garb to murder innocents, will not prevail."
Mattis promised the Defense Department would "do our best every day to protect America's promise to the world."
The ceremony included a moment of silence just before 9:37 a.m., the moment when American Airlines Flight 77 crashed into the Pentagon, killing 184 people, and a reading of the names of the 59 who died on the plane and 125 in the Pentagon.
FBI director says threat has evolved: FBI Director Christopher Wray in an interview marking 17 years since Sept. 11, said the U.S. is "safer" but the threats facing the country have "evolved."
"People think of the 9/11 threat, they think New York, they think D.C," Wray said in an interview with CBS that aired Tuesday. "Today's terrorism threat is everywhere, coast to coast, north, south, east, west. It's not just big cities."
Wray added cyber threats are "at an all-time high."
"Terrorism today moves at the speed of social media," he said.
The FBI director also said that the FBI is focused on "homegrown violent extremists."
Also today: Trump started the morning tweeting about 9/11 and the investigation into possible collusion between his campaign and Russia as he headed to a Flight 93 memorial event.
Former President Obama also marked the anniversary, tweeting: "There's nothing our resilience and resolve can't overcome, and no act of terror can ever change who we are."
And Hillary Clinton also paid tribute to the victims. "May we always remember those we lost 17 years ago," the former secretary of State tweeted. "May the love, bravery, and selflessness so many showed that day light our path forward."
MATTIS ON ASSAD USING CHEMICAL WEAPONS: HE'S BEEN WARNED: Defense Secretary James Mattis on Tuesday said Syrian President Bashar Assad has been warned against using chemical weapons on the war-torn country's last major rebel stronghold, but he declined to say whether the U.S. would take military action if such weapons were used.
"The first time around he lost 17 percent of his pointy nosed Air Force airplanes," Mattis told reporters at the Pentagon, referring to the U.S. strike on a Syrian airfield in April 2017 following a chemical weapons attack by the Assad government on residents in the northern Idlib province.
"He's been warned," Mattis added. "And so we'll see if he's wised up."
Why the situation is tense: The U.S. is monitoring heightened tensions in Syria's Idlib province, which last week was hit with roughly 30 airstrikes by Russia, a Syrian ally. After the Russian strike, the Trump administration warned Assad against using chemical weapons.
Asked if the U.S. would respond with military force if Assad uses chlorine gas on civilians in Idlib, Mattis replied: "I am not going to give that clarity."
MATTIS HEADING TO MACEDONIA: Mattis on Tuesday also announced that he plans to travel to Macedonia this weekend to "make very clear" American stands against Russian aggression as the nation considers its invitation to join NATO.
"I'm going to go out and see our Macedonian friends on a rather swift journey over there and back," Mattis told reporters at the Pentagon. "I'm going there to make very clear we stand with the Macedonian people."
A big decision: Macedonia, formerly part of Soviet ally Yugoslavia, was formally invited by NATO in July to start accession talks, which Russia has opposed. Moscow officials have said the nation could become "a legitimate target" if relations between NATO and Russia deteriorate further.
Don't forget: The Pentagon chief previously met the Macedonian defense chief at a meeting of Balkan defense heads in July in Croatia, days before the one-on-one meeting between President Trump and Russian President Vladimir Putin in Helsinki.
Following Trump's meeting, the president questioned the value of defending newest NATO member Montenegro against a Russian attack. Montenegro sits northwest of Macedonia and was also previously part of Yugoslavia. Montenegro has also accused Russia of pressuring it not to join NATO.
US IDENTIFIES FIRST TROOPS FROM RETURNED NORTH KOREA REMAINS: The U.S. has identified two American troops among the boxes of human remains that were returned from North Korea earlier this year, Reuters reported Monday.
John Byrd, who is leading the effort to identify the remains for the U.S. Defense POW/MIA Accounting Agency, said the two individuals' identities will be released in the coming days once their relatives are notified.
Reuters reported that remains from the two identified troops are believed to have been recovered from a battle near the Chongchon River. One individual is believed to be African American, based on the remains.
Forensic anthropologists have been examining the remains at a facility on Joint Base Pearl Harbor-Hickam.
Why it's significant: The announcement marks the first breakthrough in identifying troop remains since North Korea sent 55 boxes of human remains to the U.S. as part of ongoing negotiations between the two countries.
SHUTDOWN WATCH: The House and Senate have scheduled conference meetings for Thursday on two spending bill packages to limit a shutdown come October 1, reports The Hill's Niv Elis.
The first of the so-called "minibus" packages covers defense spending as well as the Labor, Health and Human Services and Education bill, which combined make up a large share of Congress's annual spending.
The second package, which lawmakers hope to pass before the new fiscal year begins, includes Interior and Environment, Financial Services and General Government, Agriculture, and Transportation, Housing and Urban Development Appropriations.
Progress? The meeting mark progress toward the goal of resolving the differences between the chambers' spending bills.
On Monday, the chambers submitted a completed conference report on an earlier set of spending bills, covering the legislative branch, energy and water, and military construction and veterans affairs. That bill is likely to see a vote this week.
The challenge: Congress must pass funding bills to cover 12 areas of spending each year, or pass a continuing resolution (CR) for those areas to keep current levels in place when the new fiscal year begins. Failure to do so results in a government shutdown.
-- The Hill: Trump to order sanctions on foreign companies that meddle in US elections: report
-- The Hill: White House warns Iran over attacks on US diplomatic missions in Iraq
-- The Hill: Mattis to visit Macedonia as it considers NATO invite
-- The Hill: Mattis on Assad using chemical weapons: 'He's been warned'
-- The Hill: US identifies first troops from returned North Korea remains
-- The Hill: FBI director: 'Today's terrorism threat is everywhere'
-- The Hill: Opinion: Dov S. Zakheim says the U.S. is still a target at war, but stronger than our foes.