US president Barack Obama has approved a new policy allowing the Central Intelligence Agency and the US military to launch drone attacks in Yemen even when the specific identities of the targets are not known.

The Washington Post, quoting administration officials, said on Thursday that the Obama approved the use of “signature strikes” this month.

It also reported that the killing of an alleged al-Qaeda fighter earlier this week near the border to Yemen’s Marib province was among the first attacks carried out under the new authority.

The shift in policy marks a significant expansion of the US drone war against al-Qaeda in the Arabian Peninsula (AQAP), which is headquartered in Yemen.

The Wall Street Journal Quoted US officials who said the amended policy allows the targeting fighters whose names are not known, but are deemed to be “high-value terrorism targets, or threats to the US.”

Yemeni officials have to give their approval for such strikes. As recently as Wednesday, however, Yemeni officials rejected a request from the CIA and US military to expand the signature strikes to target groups they describe as “fighters.”

Some congressional officials expressed concern over the use of such signature strikes, stating that they raise the likelihood of killing fighters who may not be involved in plots either to do with attacks against the US, or affiliated with al-Qaeda.

Such strikes, lawmakers argue, could inflame passions against the US among the local populations, especially tribal groups with their own militias.

“Every Yemeni is armed, so how can they differentiate between suspected militants and armed Yemenis?” one US officials reportedly asked.

All officials spoke on condition of anonymity to discuss sensitive strategic matters.