By Phil Stewart and Robin Emmott
BRUSSELS (Reuters) - The United States pressed allies on Thursday to contribute more to a U.S.-led military campaign against Islamic State that it says must be accelerated, regardless of the fate of diplomatic efforts to end Syria's civil war.
U.S. Defense Secretary Ash Carter started talks on Thursday in Brussels with more than two dozen defense ministers, including from key ally Saudi Arabia, which renewed its offer potentially to send troops into Syria.
Carter's push came a day after France delivered a rebuke to President Barack Obama, demanding that Washington show a clearer commitment to resolving the crisis in Syria where Russia is tipping the military balance in favor of President al-Bashar Assad.
The talks take place as U.S. Secretary of State John Kerry leads a diplomatic push in Munich to rescue imperiled peace efforts, which are being held despite Russian bombing raids to bolster Syrian forces around the city of Aleppo.
Carter sought to draw a line between military and diplomatic efforts. "Our focus here is going to be on counter-ISIL and that campaign will go on because ISIL must be defeated, will be defeated, whatever happens with the Syrian civil war," Carter told reporters, using an acronym for Islamic State.
"But it certainly would help to de-fuel extremism if the Syrian civil war came to an end."
The United States hopes the face-to-face gathering of coalition defense ministers will allow it to secure more support for a military campaign that aims to recapture the Islamic State strongholds of Raqqa in Syria and Mosul in Iraq.
WARPLANES, TRAINING, SURVEILLANCE
Carter plans to offer a long list of required military capabilities -- which, beyond air power, include training Iraqi forces and help with intelligence and surveillance. Carter said countries that cannot contribute militarily can help in other ways, like by choking Islamic State financing.
"We’ll all look back after victory and remember who participated in the fight," Carter said, addressing the coalition defense ministers, adding the campaign would move more swiftly "if all of the nations in this room do even more".
He also predicted "tangible gains" on the ground in the coming weeks, vague terminology that could mean anything from territorial advances to strikes against militant leaders or infrastructure.
Saudi Arabia's Brigadier General Ahmed Asseri, a military spokesman, said his country was ready to send troops into Syria if there was a consensus in the coalition. But he declined to elaborate, saying: "It is too early to talk about such options."
"Today we are talking at the strategic level," Asseri told reporters in Brussels.
Carter and U.S. defense officials also sought to manage expectations about the talks, since many ministers will not be able to make new commitments without first winning support from their parliaments. The timeline for the campaign to retake Raqqa and Mosul is also unclear.
The head of the U.S. Defense Intelligence Agency cautioned this week that Iraqi forces were unlikely to recapture Mosul this year, despite hopes by Baghdad.
Carter only said securing Raqqa and Mosul needed to happen "as soon as possible". He also acknowledged the need to grapple with Islamic State's spread beyond Syria and Iraq, particularly in Libya.
WASHINGTON FACES SCEPTICISM
Even if there is consensus on the military plan to fight Islamic State on Thursday, it is unlikely to diminish scepticism about broader U.S. policy in Syria, which has sought to limit America's role in the civil war.
French Foreign Minister Laurent Fabius on Wednesday questioned the commitment of the United States to resolving the Syrian war. Rebel groups say that while Washington has put pressure on them to attend peace talks, they see less help on the battlefield.
NATO ally Turkey has meanwhile, upbraided the United States for supporting Syrian Kurdish PYD rebels, saying Washington's inability to understand the group's true nature had turned the region into a "sea of blood".
Eager to sidestep such friction, NATO allies have focused on grappling with the humanitarian fallout from Syria's conflict at talks over the past two days.
NATO announced on Thursday it will seek to help slow refugee flows through the Aegean Sea with a maritime mission to target criminal people smuggling networks.
(Reporting by Phil Stewart and Robin Emmott, additional reporting by Sabine Seibold, editing by Peter Millership)