Mike F is right to indicate Yemen alone is clearly mission creep and one link suggests the on the ground presence was not requested by the Yemeni government, but used as an indicator of "being willing to help" in the GWOT.

Amidst all the furore in the USA over AQ camps etc in the Yemen it would be difficult for Congress and the Executive IMHO to accept any limits on the size and more of any involvement.

Watch and wait. Or Keep It Small & Simple.