Defense Secretary Lloyd Austin sent a weekend letter to Congressional appropriators urging them to pass government funding bills.

Both Hamas and Iran blame Israel for the attack that killed a Hamas leader in Tehran.

Defense Secretary Lloyd Austin revoked the plea deal bringing the death penalty back on the table for the alleged mastermind of the 9/11 terror attacks.

The Pentagon is downplaying the arrival of four Russian Navy ships in Cuba although U.S. Navy ships shadowed them as they made their way to Havana.

Defense Secretary Lloyd Austin confirmed the decision to pause munitions shipments to Israel on Wednesday. Plus, Jay O'Brien has report on attempt to oust House Speaker Mike Johnson.

ABC News' Devin Dwyer has an exclusive look at what the Pentagon is doing to combat PFAS and what's at stake in the Michigan community considered ground zero for the potentially toxic problem.

The Pentagon has announced new $6 billion military aid package for Ukraine

An exhaustive Pentagon review of decades of classified records of UFO sightings has found no links to extraterrestrials.

A U.S. official says things are still tense at the White House, citing security concerns.

A U.S. military response to the fatal drone attack in Jordan appears to be imminent. However, the Biden administration is taking steps to avoid an escalation to war.

The Pentagon announced the identities of three Army Reservists killed in a Sunday drone attack on Tower 22 in Jordan.

The Pentagon says the militants were about to target American forces with a drone attack.

Ballistic missiles were later fired from Houthi areas in Yemen, officials said.

ABC news contributor and former senior CIA field operative, Darrell Blocker joins ABC News Live anchor Diane Macedo to break down what role the U.S. could play in the next stages of the war.

The U.S. had warned Turkey the drone was flying above American forces.

A previously approved drag show to be held at Nellis AFB has been canceled by the Pentagon

Gen. Richard Edward Cavazos was the first Hispanic four-star general in the Army.

Reports have indicated suspect Jack Teixeira was driven to share classified documents to impress friends he made on the messenger platform Discord.

Two new videos were released at the rare open congressional hearing on unexplained aerial phenomena, or UAPs as the Pentagon calls them.

The Pentagon said it's working around the clock to understand the scope and scale of the leak of classified documents.

More than 30 pages of the classified material apparently containing intelligence on American adversaries and allies have been posted online.

An investigation has been launched by the Pentagon after apparently classified documents related to the war in Ukraine, Iran, North Korea and other regions were posted online.

Two separate attacks on U.S. bases are believed to have come from drones of Iranian origin.

A top official said there would be no advantage to training Ukrainians now.

As investigators uncover a significant portion of the alleged Chinese spy balloon, they said they are still looking for clues in the other flying objects that have appeared recently.

Gen. Patrick S. Ryder held a briefing after the White House announced a "high-altitude object" was shot down over Alaska on Friday.

As Chinese officials claim the airborne object is a weather balloon, U.S. officials are considering shooting it down.

In its review of hundreds of UFO incidents, Pentagon officials say they have not seen evidence so far that any are from extraterrestrials.

The entire fleet of H-47 Chinook helicopters have been grounded by the Army in order to fix a part problem in about 70 helicopters.

The U.S. Army has about 400 Chinooks in its fleet around the world, using them to transport troops and equipment as seen in the wars in Afghanistan and Iraq.

Lieutenant General Michael E. Langley was confirmed as the first Black Marine Corps four-star general.

Top Pentagon officials told a House panel that there are now close to 400 reports from military personnel of possible encounters with UFOs.

Officials said in congressional testimony they are "reasonably" sure pyramid-shaped objects in one video were drones.

U.S. Defense Secretary Lloyd Austin said Tuesday that any public statements by world leaders that the conflict in Ukraine could lead to a nuclear confrontation are "unhelpful and dangerous."

Commenting on Pentagon press secretary John Kirby's latest briefing, former U.S. defense official Mick Mulroy says it is unlikely that U.S. troops will be deployed in Ukraine.

ABC News national security and defense analyst Mick Mulroy reacts to the recent Pentagon briefing, talks sending aid to Ukraine.

The Russian warship, “Moskva,” that was badly damaged in combat was one of the ships involved in the now famous run-in with Ukrainian soldiers on Snake Island.

Defense Secretary Lloyd Austin was visually frustrated as GOP Rep. Matt Gaetz attacked his leadership.

ABC News' Stephanie Ramos is live in Ukraine breaking down the troop announcement from the Pentagon and growing tensions between Russia and Ukraine.

Retired Gen. Robert Abrams discusses tactics behind the deployment of more than 3,000 troops to Eastern Europe.

The Department of Defense issued a new report on prohibited extremist activities helping military commanders determine whether service members are actively participating in extremist activities.

The Pentagon has issued a new definition for extremism to identify active participants in prohibited extremist activities.

The Pentagon police officer slain at the Arlington, Virginia, transit center Tuesday was identified as George Gonzalez, an Iraq War veteran.

A Pentagon police officer and his assailant were killed in an incident at the Pentagon Transit Center Tuesday morning, according to two law enforcement sources.

The unpredictable 23-ton rocket is expected to crash into Earth this weekend. Some falling debris is possible. The Defense Department said there are no plans to shoot it down.

The Pentagon police officer who has been charged with murder for allegedly killing two people in Maryland this week, also pulled a gun on a homeless woman last year.

New Pentagon panel to take on sexual assault in the military as Sen. Gillibrand makes impassioned call for changes in how military deals with the issue.

Two female generals who were recently promoted to head four-star combatant commands were spotlighted during remarks in honor of International Women's Day.

Pfc. Asia Graham, 19, was found unresponsive in her barracks on New Year’s Eve.

Army officials are investigating the deaths of Staff Sgt. Jessica Mitchell, 30, and Pvt. Asia Graham, 19, in separate incidents.