The White House is considering significant military backing for France's drive against al-Qaida-linked militants in Mali, but its support for a major ally could test U.S. legal boundaries and stretch counterterrorism resources in a murky new conflict.

The United States is already providing surveillance and other intelligence help to France and may soon offer military support such as transport or refueling planes, according to U.S. officials, who stressed that any assistance would stop short of sending American combat forces to the volatile West African nation.

At the same time, the administration is navigating a thicket of questions about military support and how far it could go in aiding the French without violating U.S. law or undermining policy objectives.