Fourteen foreigners, among them a seven-member French family that includes four children, have been kidnapped by Islamist militants in Nigeria and neighboring Cameroon in recent days, a sign that the Islamist threat across North Africa is moving south.

Ansaru, a splinter group of Nigeria's extremist Boko Haram Islamist organization, claimed responsibility for the abduction of seven foreign construction workers -- two Lebanese, two Syrians, a Briton, a Greek and an Italian -- Saturday in Jama'are, northeastern Nigeria, Boko Haram's main base of operations.

There's been no claim yet for the seizure of the French family Tuesday in the Waza national park in the far north of Cameroon, an area that borders northeastern Nigeria where Boko Haram -- which means "Western education is a sin" in the Hausa language -- operates.

Counter-terrorism specialists say Ansaru was probably behind that abduction as well since, unlike Boko Haram, which has been waging an increasingly violent insurgency in oil-rich Nigeria since 2009, it has kidnapped foreigners before.

"If Boko Haram conducted the second attack, it would signal a significant shift in the group's targets and tactics," the U.S. global security consultancy Stratfor observed.

Ansaru, whose full name means Vanguard for the Protection of Muslims in Black Africa, broke away from Boko Haram in January 2012. This was supposedly over ideological differences, predominantly Boko Haram's repeated killing of "innocent" non-Muslims.

Ansaru appears to have stronger ties than Boko Haram to jihadist groups active in North Africa, particularly al-Qaida in the Islamic Maghreb, which, with its allies, is battling French-led forces in Mali.

The kidnappings are a case in point. Over the years, AQIM has raked in as much as $80 million in ransoms, mostly from European governments, for dozens of hostages seized. AQIM has executed hostages if ransoms aren't paid or rescue attempts are tried.

In 2012, Ansaru killed a British engineer and an Italian kidnapped in northern Nigeria when Nigerian troops bolster by British Special Forces mounted a rescue operation.

But more importantly, Ansaru, again unlike Boko Haram, has declared its intention to take its struggle beyond Nigeria's borders, fueling long-held fears by Western intelligence services that AQIM plans to extend its operations into sub-Saharan Africa.

Ansaru's links with AQIM were underlined by the Nigerian group's release of its communiques through Agence Nouakchott d'information, Mauritania's state news agency.

During the Jan. 16-21 attack on the In Amenas natural gas complex in the Algerian desert, in which scores of foreigners were held hostage, the agency served as the mouthpiece for Mokhtar Belmokhtar, the AQIM leader who masterminded the attack in which nearly 40 foreigners were slain.

It's possible the recent kidnappings, like the In Amenas attack, are in response to France's Jan. 11 military intervention in Mali, a former French colony where Islamists seized control of the entire northern region in April 2012.

France, the former colonial power, has long been a target for Algerian Islamists.

AQIM is largely based in Algeria and most of its commanders, like Belmokhtar, are veterans of Algeria's civil war between Islamists and the military-backed regime that raged throughout the 1990s.

At least 15 French hostages are being held by Islamist groups in northwestern Africa.

"Nearly all the Ansaru attacks since December 2012 ... have targeted French nationals or those supporting French operations in Mali," Stratfor noted in an analysis published Thursday.

"This has raised the fear that widespread kidnappings will be a fallout from the Mali intervention."

Boko Haram, whose political agenda is more localized and aimed at establishing Islamic law in Nigeria's Muslim north, isn't known to have conducted any kidnappings.

It concentrates on killing Christians and Nigeria's security forces, usually using suicide bombings and assassinations and burning down churches.

"Ansaru's attacks ... have consisted of raids by gunmen against hardened targets," Stratfor observed.

"A platoon-sized element typically assaults the compound where hostages will be abducted, or prisoners freed."

Western security experts are studying Ansaru hard these days because, as Stratfor notes, AQIM "may work more closely with Ansaru in an attempt to orchestrate its activities into a broader strategy ...

"Ansaru's development is significant ... its operations reach beyond Nigeria's borders.

"Ansaru could also extend AQIM's network farther south ... and the group's rise could easily negate the gains made against militants in northern Mali."