France indicated that it would consider supporting a partial no-fly zone over Syria, turning the screws on President Bashar al-Assad's regime as fighting rages in Damascus and second city Aleppo.
French Defence Minister Jean-Yves Le Drian however warned that shutting all of Syria's air space would mean "going to war" and would require a willing international coalition that has not yet materialized.
Speaking on France 24 television, Le Drian called for considering a partial closure of Syria's air space, as suggested by US Secretary of State Hillary Clinton.
"A possible delimited zone around which there could be a ban of some sort, such as suggested by Hillary Clinton, should be studied," he said.
Le Drian said a "global no-fly zone" over Syria was ruled out as it would be tantamount to grounding all Syrian aircraft, which could not be done unless there was "an international coalition capable of doing it."
Foreign Minister Laurent Fabius also indicated separately in a press conference that France was weighing a possible no-fly zone.
In his interview, Le Drian stressed that France would not accept a political transition in Syria without Assad stepping down. "His departure comes first," he said.
The French defence chief also stressed that France would not get involved without a UN mandate.
"We would only be able to intervene in Syria... if there are international legal norms," he said. "Without international legal norms, we can't do anything."
Clinton said earlier this month that the issue of imposing safety and no-fly zones around ravaged cities such as Aleppo "need greater in-depth analysis." She said Turkey and the United States had agreed to deliberate further moves.
Syrian ally Russia has rejected the proposal.
Turkish and US officials Thursday held their first "operational planning" meeting aimed at hastening the end of Assad's regime.
Clinton announced plans for the forum following talks in Istanbul on August 11 as Washington signalled it was looking for new ways to put pressure on Assad after his traditional allies Beijing and Moscow blocked action at the UN Security Council.