ABUJA, Nigeria (AP) — Jihadi extremist groups, including Boko Haram and one of its factions, have been blamed for intensified attacks targeting Nigeria's military bases in the northeast of the country in the last week.

At least two officers and several soldiers have been killed in the attacks, which analysts say shows a remarkable level of coordination.

Over the weekend, Islamic extremists launched at least six attacks in Borno and Yobe states and in the wider Lake Chad region, spiriting away trucks and military hardware from the bases, according to security analysts and security reports.

The Nigerian military said in a statement that the latest attacks between Sunday and Monday were an “attempt by the terrorists to overwhelm troop positions.”

Military spokesman Sani Uba said late Monday that the troops lost an unspecified number of soldiers and a military officer, without providing further details. It adds to a death toll of several soldiers and at least one officer in the past week. Security analysts estimate at least four military officers have been killed in that period.

Africa’s most populous country has long struggled to contain the jihadi violence in its northeast. After launching an insurgency in 2009, Boko Haram has grown into different factions, including the Islamic State West Africa Province, or ISWAP, which is backed by the Islamic State group. The crisis has overstretched the Nigerian military, which also battles other security crises across the conflict-battered north.

The attacks have angered Nigerians, with many accusing President Bola Tinubu's government and the ruling party of prioritizing next year's presidential election in which Tinubu is expected to seek reelection.

While ISWAP has staged a growing number of attacks against the military in recent months, observers say this is the first time in recent history that the group has successfully launched simultaneous attacks of this scale in the region.

The attacks show “a remarkable level of coordination” from the group, according to Vincent Foucher, senior research fellow with France’s National Center for Scientific Research who has extensive knowledge of the conflict.

Videos published by ISWAP showed massive weaponry and ammunition, as well as dozens of motorcycles and vehicles that the extremists said were captured during the raids. The Associated Press couldn't independently verify the details of the video.

A key goal of the jihadis is to restock their weapons arsenal, said Taiwo Adebayo with the Africa-focused Institute for Security Studies.

“When they hit those camps, they strip the base of weapons, burn it down and retreat into the forests,” Adebayo said.

Malik Samuel, a Nigerian security researcher with Good Governance Africa, said that “as long as military bases remain vulnerable to being overrun, ISWAP does not need to spend money buying arms."

The attacks are happening despite a boost from the United States, which has deployed at least 100 troops to support the Nigerian military with training and logistics. That deployment is part of a new security partnership between Nigeria and U.S. that came after U.S. President Donald Trump alleged that Christians are being targeted in Nigeria’s security crisis.

Since the U.S. began to intervene in the security crisis in December last year, its Intelligence, Surveillance and Reconnaissance, or ISR, flights have helped the Nigerian military to intensify aerial bombardment of jihadi hideouts, officials have said.

However, ISWAP continues to mount coordinated attacks which highlight their sophistication and show how dominant they’ve become, Adebayo said.

A major challenge in the region remains the limited presence of security forces and the government in conflict hot spots.

Despite its successes against jihadi groups in the region, the Nigerian military lacks the capacity for sustained operations and quickly moves on to other hot spots, Adebayo said.

“So the (armed) groups are quickly regrouping and delivering attacks elsewhere,” he said.