The United States announced it will provide transport planes to French forces fighting in Mali but has yet to decide if it will offer refueling tankers for French warplanes, officials have said.
"We've agreed to help the French with airlift. And we're now working out the details," a defence official, who spoke on condition of anonymity, told the AFP news agency on Thursday.
However, there was still no final approval on a request from Paris to help refuel French warplanes with American tanker aircraft, he and another defence official said.
The US government had already agreed to bolster intelligence sharing to assist the French, including information from surveillance drones and spy satellites, officials said.
Hillary Clinton, the US secretary of state, confirmed the move to put intelligence resources and transport planes at the disposal of French troops.
"We are supporting the French operation in Mali with intelligence and airlift," she said in Washington after meeting Somali President Hassan Sheikh Mohamud.
The American transport planes would likely be used to ferry French tanks, armoured vehicles and other heavy equipment.
The United States has a vast fleet of military transport planes at a network of bases in Europe and elsewhere, along with refueling tankers, which are in increasingly short supply in France and other NATO countries.
The first West African regional forces also arrived in Mali on Thursday to reinforce French and Malian troops battling to push back al-Qaeda-linked rebels after seven days of French air strikes.
A contingent of around 100 Togolese troops landed in Bamako and was due to be joined by Nigerian forces already en route.
Nigerien and Chadian forces were massing in Niger, Mali's neighbour to the east.
The scrambling of the UN-mandated African mission, which previously had not been due for deployment until September, will help France, the former colonial power in Mali.
President Francois Hollande ordered the intervention on the grounds that the Islamists who had taken over the poor West African country's north could turn it into a "terrorist state" which would radiate a threat beyond its borders.
Hollande has pledged they will stay until stability returns to Mali but, in the first apparent retaliatory attack, al-Qaeda-linked militants took dozens of foreigners hostage at a gas plant in Algeria, blaming Algerian cooperation with France.
A total of 2,500 French troops are expected in Mali but Paris is keen to swiftly hand the mission over to West Africa's ECOWAS bloc, which in December secured a UN mandate for a 3,300-strong mission to help Mali recapture its north.
Military experts say France and its African allies must now capitalise on a week of hard-hitting air strikes by seizing the initiative on the ground to prevent the insurgents from withdrawing into the desert and reorganising.