The Taliban has halted the polio vaccination campaign that was scheduled to be distributed to over 161,000 children starting on Wednesday, citing worries that the U.S. drone strikes are indicative of a possible undercover CIA operation tied to the vaccine campaign.

The fears stem from an operation last year in which the CIA acted with Dr. Shakil Afridi, who used the vaccine campaign as a means to try and flush out Osama bin Laden with a door-to-door drive in Abbottabad. Dr. Afridi has been convicted for his part in the operation and was sentenced to 33 years by a tribal court.

Polio is still heavily prevalent in Pakistan, most notably in the North Waziristan tribal belt; this is where Pakistani officials are focusing their crackdown since the U.S. drone strikes. Taliban leader Hafiz Gul Bahadur says no vaccines will be given until he gets assurances that the drone strikes will cease.

Polio ran rampant in Pakistan last year; almost 200 new cases were reported last year, the highest amount at that time in the world. UNICEF says 143,000 of the area’s 161,000 children were reached by the last round of vaccinations earlier this year, which were given from June 4th to the 6th, but the ban on the upcoming round will hamper all their work.

The CIA has come under fire in recent years by aid workers for their use of health care providers in their operations, saying it only leads to undue suspicion towards the people who really just want to help.

Dr. Muhammad Sadiq, the North Waziristan surgeon general, said he had received Taliban orders to cancel the vaccination drive and is only carrying out his duty.

“Under these circumstances, we cannot continue,” he said in a telephone interview.