ISLAMABAD (AP) — A suicide bomber targeted a security convoy in a former Pakistani Taliban stronghold in northwestern Pakistan, killing four soldiers, officials said Tuesday.

No one claimed responsibility for the attack on Monday in North Waziristan, a district in Khyber Pakhtunkhwa province that borders Afghanistan. A military statement said four soldiers were martyred in the attack and that an investigation was underway.

The assault came a day after a late night roadside bombing in eastern Afghanistan struck a vehicle carrying members of the Pakistani Taliban, killing a senior leader and three other militants traveling with him.

The Pakistani Taliban blamed intelligence agents for the high-profile killing on Sunday night, without offering evidence or elaborating.

The slain senior leader of the Pakistani Taliban — the Tehrik-e-Taliban Pakistan or TTP — was Abdul Wali, also widely known as Omar Khalid Khurasani. On Tuesday, TTP in a statement confirmed the killing of Khurasani, who had a $3 million U.S. bounty on his head. He was a tough negotiator and was part of the TTP team that has been holding peace talks with Pakistani officials in Afghanistan’s capital since May.

Khurasani’s death was a heavy blow to the TTP, which is in talks with the Pakistani government amid an ongoing cease-fire, announced in May. Isolated militant attacks have continued, though the TTP has not claimed responsibility for any of them since the truce first went into effect. The talks are being hosted by the Afghan Taliban.

Two local Pakistani intelligence officials told The Associated Press that Monday’s suicide bombing in the town of Mir Ali also wounded an unspecified number of civilians and soldiers. The officials would not elaborate and spoke on condition of anonymity because they were not authorized to speak to the media on the record.

North Waziristan and other former tribal regions in northwestern Pakistan were long a base for the Pakistani Taliban and other militant groups until the army claimed a few years back that it cleared the region of insurgents. Occasional attacks have continued, however, raising concerns the Pakistani Taliban are regrouping in the areas.

The Pakistani Taliban are a separate group but allies of the Afghan Taliban, who seized power in Afghanistan a year ago as the U.S. and NATO troops were in the final stages of their pullout.

The Taliban takeover in Afghanistan has emboldened the Pakistani Taliban to intensify their demands for stricter enforcement of Islamic laws in Pakistan, release of their members from government custody, and a reduction of military presence in Pakistan’s former tribal regions.

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