International and Iraqi forces continue their push against ISIS militants in Iraq, Syria, and now Libya.
Here’s a rundown of the latest developments, on and off the battlefield:
Egypt launches second wave of airstrikes on ISIS in Libya
Egyptian warplanes staged a second wave of airstrikes against ISIS targets in Libya on Monday in retaliation for the slaughter of 21 Egyptian Christians by ISIS militants, Egypt’s state-run Ahram Online reported, citing security officials.
The airstrikes came after an earlier wave that struck ISIS camps, training areas and weapons depots, the military said.
“Avenging Egyptian blood and punishing criminals and murderers is our right and duty,” the Egyptian military said in the statement, which was broadcast on state television.
Video appears to show beheadings of Egyptian Christians
The bombing raids came after ISIS released a gruesome video Sunday that appeared to show ISIS militants beheading men they said were Christians on a beach.
The slickly produced video shows the apparent mass killing, with jihadists in black standing behind each of the victims, who are all dressed in orange jumpsuits with their hands cuffed behind them.
Twenty-one Egyptian Christians were kidnapped in the Libyan coastal city of Sirte in two incidents in December and January. They were reportedly from impoverished villages and went to Libya looking for work.
Although the ISIS video showed around a dozen men being beheaded, Egyptian officials said that all 21 Christians were believed to have been killed.
Key base attacked
An Iraqi tribal leader said Saturday that ISIS militants are gaining ground in Anbar province.
Sheikh Naim al-Gaoud, a Sunni Muslim leader of the Albu Nimr tribe, called for more U.S. intervention – including ground troops, arming tribes directly or at least pressuring the Iraqi government to give the tribes more firepower.
Anbar province is just west of Baghdad, meaning a decisive ISIS victory would put militants on the footsteps of the Iraqi capital. It’s home to the strategic Ayn al-Assad Air Base, which came under attack Friday.
Talking about that battle, Pentagon spokesman Rear Adm. John Kirby said 20 to 25 people – most, if not all, of whom were wearing Iraqi military uniforms and were led by suicide bombers – attacked the nearly 25-square-mile base.
“It looks like (ISIS militants) at least got to the outer base limits,” Kirby said.
At least 13 Iraqi soldiers died in the assault, said al-Gaoud, which ended with Iraqi ground forces killing all the attackers.
U.S. troops were on the base at the time, but “several kilometers” from where the fighting happened, Kirby said. The U.S. military did deploy attack helicopters in that ISIS assault, but the Apaches returned safely without firing a shot, military sources said.
U.S. gunships support Iraqi ground forces battling ISIS
American helicopter gunships were also involved in a fight supporting Iraqi ground forces about 15 kilometers (9 miles) north in the Anbar town of al-Baghdadi, according to sources.
Al-Gaoud, the Albu Mimr tribal leader, said militants killed at least 25 Iraqi police officers during their assault on that town Thursday and Friday.
On Saturday, the U.S. military said al-Baghdadi was contested, as Iraqi forces fought back.
Widow of Paris kosher market gunman in Syria, ISIS says
An issue of a magazine published by ISIS claims that Hayat Boumeddiene, the widow of Paris kosher supermarket gunman Amedy Coulibaly, is in Syria.
After the attack on January 9, in which four people were killed, European authorities launched a search for Boumeddiene, who is suspected of having aided Coulibaly in plotting it.
The ISIS magazine includes a purported interview with Boumeddiene, but does not offer a photo or other evidence that she is in Syria.
Western investigators, however, have said they believe she crossed into Syria from Turkey around the time of the attacks.
Obama requests formal authority for ISIS fight
President Barack Obama on Wednesday asked Congress to formally authorize the use of military force in the war against ISIS.
What’s in the proposed military force authorization? And what’s the point?
The President declared that congressional passage of the measure makes the U.S. strongest in the fight, and that while the mission is difficult, the terrorist group “is going to lose.”
He said the bill includes authority for a “systemic and sustained campaign of airstrikes,” support and training for forces on the ground and humanitarian assistance. Obama made it clear, however, that the authorization for the use of military force, or AUMF, does not call for the deployment of ground troops in Iraq or Syria.
It’s the first time in 13 years that a U.S. president has sought this kind of authorization.
Why doesn’t war proposal include Jews as ISIS targets?
As Obama’s war proposal is debated in Congress, one lawmaker keyed in on what he called an omission.
The proposed authorization for the use of military force singles out several ethnic groups threatened by ISIS: Iraqi Christians, Yazidis and Turkmens, but says nothing about Jews.
Rep. Lee Zeldin, the only Jewish Republican member of Congress, is questioning whether Jews were deliberately not listed.
“I see an understanding, a recognition in the resolution with regards to ISIS attacks on Muslims, on Christians and others, and I didn’t see a reference to Jews,” Zeldin said. “And one of the efforts I’ve been involved in is trying to raise awareness for the rising tide of anti-Semitism.”
Foreign fighters flocking to join ISIS
A top U.S. counterterrorism official is warning that the number of foreign fighters joining the ranks of ISIS is growing at an alarming rate, and that scores of them are from the United States.
Nicholas Rasmussen, director of the National Counterterrorism Center, told the House Homeland Security Committee on Wednesday that more than 20,000 fighters from more than 90 countries have traveled to the ISIS battlefield.
Foreign fighters are traveling in greater numbers to Syria now than the number who went to the conflicts in Afghanistan, Pakistan, Iraq, Yemen or Somalia in the past two decades, Rasmussen said.
Of those fighters, an estimated 3,400 are believed to have come from Western countries, including more than 150 from the United States, officials say.
Was U.S. hostage made an ISIS bride?
Last week, the family of American hostage Kayla Mueller confirmed that she was dead. The family had kept news of her capture out of the media, and had been in contact with ISIS for some time trying to win her release. ISIS sent the family a private message with information about her death.
Now, U.S. intelligence and government officials say Mueller possibly was paired with a male ISIS fighter during her captivity.
The officials, speaking on condition of anonymity, cited unspecified intelligence gleaned about the case. A U.S. intelligence official said it was unclear whether Mueller was sold or forced into the pairing.
Intelligence suggests Mueller may have been given to an ISIS fighter as a sort of bride, one U.S. government official said.
ISIS’ high-profile hostages
Most high-profile ISIS victims have come from a number of nations and backgrounds. One thing that unites them is that they were on a mission in Syria or Iraq – to distribute aid, provide medical care, report on the situation, or to fight militarily.
CNN’s Jethro Mullen profiles some of those killed by ISIS
This collection of the latest developments is drawn from reporting and writing from across CNN’s platforms.