United States President Barack Obama is ruling out any large-scale deployment of American combat troops in Iraq and Syria, the White House says.
Islamic State fighters now control half of Syria, and are gaining momentum in Iraq's key Anbar province - close to where New Zealand and Australian troops are training Iraqi soldiers.
The United States has acknowledged that Islamic State's recent capture of the cities of Ramadi in Iraq and Palmyra in Syria represents a setback.
However the BBCs Jon Sopel reports there is no indication of any change to US strategy in the region.
"There is great criticism of the strategy but no one is coming up with what the Plan B should be, there is no way that President Obama is going to send 150,000 troops to re-invade Iraq and invade Syria and so you're left with the existing strategy with maybe a bit of amplification.
"You know the president said at the outset, the twin strategy was to degrade and destroy IS, well the spokesman admitted this afternoon that destroying IS was not going to happen while this president was in the White House and so you're left with a more modest aim of degrading and that is still a very long way off."
America's strategy is for coalition troops - including New Zealanders - to train local fighters and provide air support, but it won't commit more ground troops.
A State Department spokesperson Marie Harf said there have been setbacks but President Obama was sticking to current policy.
"We have a strategy that is choking off their funding, that is taking off their fighters, that is cutting off ways for them to get more foreign fighters, that's taking them off the battlefield every single day including right now," she said.
"The US airforce that is operating in and around Ramadi searching for ISIL targets, and is going to do so until Ramadi's retaken."
The United Nations says the Syrian Government stopped civilians fleeing Palmyra as IS fighters advanced on the city.
The UN is also expressing concern that the militants will now destroy the 2000-year-old ruins in Palmyra.
The Syrian Government has contradicted the UN's evacuation claims.