File photo taken on April 27, 2018 shows a wreckage of a vehicle after a bomb attack by Boko Haram militia in Maiduguri, Nigeria, April 27, 2018. (Xinhua/NAN)

ABUJA, Nov. 30 (Xinhua) -- The Nigerian army on Thursday made a revelation that terror group Boko Haram has gone hi-tech in attacking military formations in the country's northeast region.

In a statement reaching Xinhua in Abuja, army chief Tukur Buratai said the Boko Haram now uses drones and mercenaries during attacks, a trend which poses serious security threats to the country.

"In the last two to three months, we have noticed daring moves by the terrorists, increased use of drones against our defensive positions and infusion of foreign fighters in their ranks. These potent threats require us to continually review our operations," Buratai said.

He confirmed the Boko Haram terrorists had attacked at least five military locations between Nov. 2 and 18, adding, however, the attacks were successfully repelled by the troops.

Boko Haram has been trying since 2009 to establish an Islamist state in northeastern Nigeria, in the process killing tens of thousands of people and displacing millions of others.

The group in the Lake Chad Basin has posed enormous security, humanitarian and governance challenges, according to the United Nations.

Four countries caught up in the insurgency are Cameroon, Chad, Niger, and Nigeria. The UN said Boko Haram has displaced nearly 2.4 million people in the Lake Chad sub-region.