U.S. Officials: Paris Attackers May Have Had ‘Military-Type Training’

— -- The deadly attack on a satirical magazine in Paris this week reflected a level of sophistication authorities have never seen before in a terrorist attack carried out with guns and other small arms, the FBI and Department of Homeland Security said Friday.

The assailants “acted with confidence and exhibited skill in weapons handling,” and they “were equipped with tactical gear and assault rifles and moved and fired in a manner indicative of prior training,” the U.S. agencies said in a joint intelligence bulletin issued to federal, state and local law enforcement partners across the country.

In fact, the attackers may have “conducted some level of pre-operational surveillance,” on the offices of magazine Charlie Hebdo, according to the bulletin, obtained by ABC News.

Within hours of the document being issued by the FBI and DHS, al Qaeda’s offshoot in Yemen, Al Qaeda in the Arabian Peninsula, claimed in a statement to the Associated Press that it directed Wednesday’s attack, and the group posted a video online calling France a "beacon of blasphemy.”

According to the bulletin, U.S. authorities are working with their French counterparts “to learn more about the suspects involved in the attack and potential connections to international terrorist groups and/or travel to known combat zones.”

The bulletin expressed fresh concerns over Americans who join terrorist groups overseas and “could gain combat skills, violent extremist connections, and possibly become further radicalized or persuaded to conduct organized or lone offender extremist-style attacks, potentially targeting the United States and its interests abroad.”

In addition, the bulletin noted “the proliferation” of propaganda online by al Qaeda and the Islamic State – or ISIS – which encourages foreigners to travel to conflict zones and then “initiate attacks against the West,” and inspires “Western-based persons to initiate attacks if they are unable to travel,” as the bulletin put it.

While aviation and mass transit remain “attractive targets” for terrorists, targets within private industry – including media organizations – “may become of particular interest to groups and individuals seeking to conduct attacks,” the bulletin concluded.

While the bulletin identifies no specific threat to the U.S. homeland tied to the attack in France, it nonetheless encourages law enforcement to “remain vigilant,” and it identifies potential indicators of suspicious activity.

In recent years, bulletins like the one issued Friday have become somewhat routine ahead of major U.S. holidays and after major terrorist incidents across the world.

Law enforcement officials contacted by ABC News noted they have been training for years to respond to an attack like the one seen in France this week.

Asked Thursday about concerns to the homeland in light of Wednesday’s assault, President Obama’s homeland security adviser, Lisa Monaco, told ABC News the U.S. government has “no information about any threats to the homeland from this.”

“But … we want to make sure we're maintaining vigilance,” she added. “And that's what we're going to do."