Before the start of business, Just Security provides a curated summary of up-to-the-minute developments at home and abroad. Here’s today’s news.

ORLANDO NIGHTCLUB ATTACK

Orlando nightclub killer Omar Mateen was radicalized over the internet, President Barack Obama and the FBI have confirmed, separately. Obama added that “there is no clear evidence that he was directed externally,” write The Guardian’s Ed Pilkington and Dan Roberts.

Mateen is an example of “precisely the threat” that has vexed the FBI in the past few years: a terrorist living in the US whose “self-radicalization” is hard to spot,” say Devlin Barrett and Dan Frosch. At the same time, the “sheer volume” of people in the US who have “expressed some interest in radicalism but don’t pose an obvious threat” creates a huge challenge for investigators. [Wall Street Journal]

It is “wolf dens, not lone wolves” that are the norm in US Islamic State cases, contrary to the warnings by officials following Sunday’s attack, report Joseph Ax and Kristina Cooke for Reuters. A review of the approximately 90 cases brought since 2014 shows that three-quarters of those charged were allegedly part of a group of co-conspirators, who met in person to discuss their plans. Otherwise, defendants were almost always in contact with other terrorist sympathizers, via text, email, or networking websites.

Mateen is the third person to carry out a terrorist attack after being scrutinized by the FBI, including the Boston Marathon bombing and the attack on a contest to draw the prophet Muhammad last year. [The Washington Post’s Adam Goldman, Matt Zapotosky, and Mark Berman] In light of such scrutiny over the FBI’s previous investigations of Mateen, Director James Comey is promising to launch a review to identify whether it missed crucial warning signs that he would turn violent.

US House members will receive a classified briefing on the Orlando shooting at 3pm this afternoon from FBI Director James Comey, Secretary of Homeland Security Jeh Johnson and National Counterterrorism Center Director Nick Rasmussen. [The Hill’s Cristina Marcos]

IRAQ and SYRIA

US commanders in Iraq have used Apache attack helicopters in combat near Mosul, the first time the aircraft have been called into action against the Islamic State, Defense Secretary Ash Carter revealed yesterday. The use of the low-flying aircraft adds another role for US troops fighting against the Islamic State, but at increased risk, reports Kristina Wong. [The Hill]

More than 500 suspected Islamic State members have been arrested since the operation to retake Fallujah began two weeks ago, according to Iraq security officials, who claim fighters are attempting to leave the city hidden among escaping civilians. [AFP]

US-led airstrikes continue. US and coalition forces carried out 13 airstrikes against Islamic State targets in Syria on June 12. Separately, partner forces conducted 19 strikes against targets in Iraq. [US Central Command]

EUROPE

The Islamic State has claimed responsibility for the fatal stabbing of a French police officer and his partner in Paris on Monday evening. The perpetrator, who reportedly claimed allegiance to the terrorist organization, was shot by police, who rescued the partner’s three-year-old son. Sources close to the investigation have said that the suspect is Larossi Abballa, a 25-year-old who was sentenced in 2013 for links to a jihadist network that sent recruits to Pakistan. [France 24] Two people believed to be “close to the suspected attacker” have been detained in connection with the attack, according to officials. [AP]

More than 100 individuals have recently been arrested on suspicion of posing a threat to France, according to France’s interior minister. [AP]

The Islamic State is viewed as the biggest threat by Europeans, slightly ahead of climate change and economic instability, and far outpacing tensions with Russia, according to a new survey, writes the Wall Street Journal’s Julian E Barnes.

OTHER DEVELOPMENTS

President Obama has ruled out using an executive order to close Guantánamo Bay detention center, according to anonymous sources. White House lawyers reportedly studied the option but could not come up with a convincing legal argument or a politically appealing case to sell the idea. This decision, reports Rebecca Kheel, “effectively extinguishes President Obama’s last chance to fulfil a promise from his first presidential campaign.” [The Hill]

The FOIA reform bill will soon be sent to the White House, where it is expected to be signed into law by President Obama. The bill, which has been considered by both houses of Congress for several years now, contains a number of reforms, including a presumption in favor of disclosure. The bill would also create a centralized portal for FOIA requests across the government. [Politico’s Josh Gerstein]

NATO will formally approve a plan to send four multinational battalions to the Baltic States and Poland to shore up their defenses against Russia today. Secretary-General Jens Stoltenberg said yesterday that the battalion “will send a clear signal that NATO stands ready to defend any ally.” There was no immediate reaction from Moscow. [AP’s John-Thor Dahlburg and Monika Scislowska]

The head of NATO has welcomed indications that European countries and Canada are set to increase their military spending by 1.5% this year, calling it a step in the right direction. The small increases come after years of declines, of which US political figures have been increasingly critical. [Wall Street Journal’s Julian E Barnes]

Pakistan is considering purchasing used F-16 fighter jets from Jordan after a plan to buy 8 of the same aircraft from the US fell through because Congress refused to finance it. [Reuters’ Asad Hashim]

The Philippine president has condemned the “brutal and senseless murder” of Canadian Robert Hall by militant Islamist group Abu Sayyaf. Hall was kidnapped along with three others last September. A fellow Canadian, John Ridsdel, was killed by the group in April after a multi-million dollar ransom deadline expired. Hall’s Filipino partner Marites Flor and Norwegian Kjartan Sekkinhstad were also taken hostage. [BBC]

Both sides in the South China Sea dispute should take “a long-term perspective” in trying to solve it, China’s foreign minister told his counterparts in the Association of Southeast Asian Nations, four out of ten members of which have claims in the region that overlap with China’s own. [AP]

North Korean hackers stole US jet fighter designs and photos of parts of spy planes from a South Korean company, according to authorities in Seoul. Over 4,000 documents relating to the defense industry were reportedly stolen in hacks on two companies that began in 2014 and were only discovered earlier this year [Wall Street Journal’s Alastair Gale and Kwanwoo Jun]

New Findings in the investigation into crashed EgyptAir Flight 804 suggest there was no onboard explosion before it plunged into the Mediterranean Sea on May 19, killing 66 people. Instead, the plane appears to have veered off-course, turning left before rolling to the right and completing a full circle. This does not explain how it ended up in the sea, however. [Wall Street Journal’s Dahlia Kholaif et al]

The gunmen who attacked a national guard base in Kazakhstan last week listened to a radio address broadcast from Syria urging them to wage holy war beforehand, according to Kazakhstan’s interior minister. [Reuters’ Raushan Nurshayeva and Olzhas Auyezov]