A group of prominent Muslim clerics is warning it will call for jihad, or holy war, if the U.S. sends troops to fight Al Qaeda in Yemen.

The group of 15 clergymen includes the highly influential Sheik Abdul-Majid al-Zindani, whom the U.S. has branded a spiritual mentor of Usama bin-Laden.

Their warning goes straight to the Yemeni government's dilemma in cooperating with Washington against an Al Qaeda offshoot in the country. In doing so, the regime must avoid upsetting al-Zindani and other radical figures whose support it needs to stay in power.

President Barack Obama has said he does not plan to send American combat troops to Yemen, though Washington is increasing counterterrorism aid and training to Yemeni forces.