After seizing power in August, the west African country's military government faces its first big security test.
The cat-and-mouse game across the West African nation's vast desert areas is the first big security test for Mauritania's new military government, which seized power in an Aug. 6 coup that overthrew the country's first democratically elected president.
The US has offered funds and training to Mauritania to help it fight the Al Qaeda-linked group, but cut such aid after the coup.
Agence France-Presse (AFP) quoted a Mauritanian lawmaker as saying the military was confident it would catch the attackers by blocking desert transit points and using air reconnaissance.
While Mauritanian security sources originally said 12 soldiers had been killed in the ambush, they now say the men are likely hostages, AFP reported the lawmaker as saying:
"The 12 men, including a captain, are in the hands of the criminals who would undoubtedly try to use them as cover in their escape and for possible ransom demands," [the lawmaker] said.
Experts say the attackers are likely only to be able to travel at night and would have needed at least five days to reach the border with Algeria or Mali.
If that's correct, the militants would not be able to reach the border until Saturday at the earliest.