In both word and deed, the Bush administration indicated this week that it is escalating its military role in Afghanistan amid signs that increased clashes among competing warlords and challenges by rival militias to the U.S-installed interim government could tip Afghanistan back into chaos.

U.S. special envoy Zalmay Khalilzad told reporters in Kabul that possible new moves include expansion of the British-led 4,500 member multinational peacekeeping force patroling the capital city, sending U.S. military advisors to the scene of potential conflicts and speeding U.S. aid and training for an Afghan national army.

Meantime U.S. aircraft twice bombed rival militias that reportedly attacked forces allied with the interim government. The raids were apparently the first time U.S. air power had been used directly in defense of the interim government headed by Hamid Karzai.

Also last week, the Pentagon admitted that U.S. forces mistakenly killed 21 Afghan civilians in a raid north of Kandahar in January – one in a number of similar tragedies since the U.S. began bombing Afghanistan last October.

Defense Secretary Donald Rumsfeld tried to excuse the incident on the basis of “untidy” wartime conditions, but a December report by University of New Hampshire professor Marc Herold put the civilian casualties from the U.S. war at nearly 3,800.

Karzai has repeatedly asked that the multinational peacekeeping force be increased and that its role be expanded throughout Afghanistan. But the 11 contributing countries have so far not agreed. Khalilzad said the U.S. doesn’t plan to join the peacekeeping force, but that the Bush administration might ask the member countries to send more troops and expand their area of operations.

Armed clashes between rival warlords and tribal militias – which ravaged Afghanistan following the defeat of the People’s Democratic Party-led government in 1992 – have resurfaced since the U.S. attack that drove out the Taliban last fall.

Clashes have occurred in southern Afghanistan among Pashtun leaders, and also among Tajik, Uzbek and Hazara groups, which made up the anti-Taliban Northern Alliance. About 3,000 U.S. troops are currently based at the southeastern city of Kandahar, along with an undisclosed number of Special Forces.

A recent CIA report warned that Afghanistan could fall into violent chaos again if ways are not found to restrain the competition among the warlords and to control ethnic tensions. The CIA report concluded that renewed civil war is not imminent, but “seeds of civil conflict are still present.”