More than 100 Afghan security force personnel have been killed over the last two weeks amid a surge of Taliban attacks following Washington’s announcement it would pull all U.S. troops out by Sept. 11, officials said on Thursday.

Senior Afghan officials say the Taliban is putting on a show of force and seeking to gain territory as foreign forces pull out. The Taliban has waged a two-decade-long insurgency since being ousted from power by U.S.-led foreign troops in 2001.

According to two senior security officials, around 120 Afghan security forces personnel, 65 civilians and over 300 Taliban fighters have been killed in the last 15 days of fighting, and scores more wounded across the country.

A spokesman for the Interior Ministry, Tariq Arian, said the Taliban have carried out at least six suicide bombings and several targeted killings and had planted 65 roadside bombs to target government troops.

He added that more than 60 civilians have been killed and 180 injured. He did not provide figures for casualties suffered by security forces, in keeping with usual government practice.

Dozens of Taliban fighters, including several commanders, have been killed during operations, Arian said.

Taliban spokesman Zabihullah Mujahid rejected the government’s claim the group had inflicted civilian casualties, saying these were caused by air and ground operations by Afghan forces. He did not comment on the deaths of Taliban or security forces.

President Joe Biden earlier this month announced the United States would begin its final military withdrawal on May 1, completing it by Sept. 11. Foreign troops under NATO command will also withdraw, NATO allies agreed.

The White House said on Thursday that American troops had started withdrawing from Afghanistan, confirming comments made over the weekend by a senior U.S. general.

Since Biden’s announcement, violence has increased by nearly a quarter around the country, with Taliban attacks reported in 21 of the 34 provinces, an Afghan Defence Ministry spokesman said.

“We are already in the middle of Taliban’s annual spring offensive but we are prepared and conducting our operations,” said a senior government official, who asked not to be named.

Afghan chief of intelligence Ahmad Zia Siraj said the Taliban have increased violence “to the highest level” in recent days.

Top security leaders flew to the central province of Ghazni on Thursday to assess the situation amid reports of the Taliban amassing fighters in the area to overrun the strategic province.

Peace efforts stalled after the Taliban and the Afghan government began talks in the Qatari capital Doha last year. Washington pushed for a summit in Turkey this month but that was postponed because the Taliban refused to participate, and no new date has been set.

The troop pullout deadline of Sept. 11 is later than a May 1 deadline agreed between the Taliban and United States in Doha last year. The Taliban, which has not attacked foreign troops since the Doha agreement, has called the delay unacceptable.