The United States will cooperate with Russia in fighting the Islamic State, but only if Moscow accepts the US dual track political strategy of pushing to replace Syrian President Bashar Assad, Secretary of State John Kerry said on Tuesday.

WASHINGTON (Sputnik) — Islamic State spokesman Abu Mohammad al-Adnani called on the Muslim youth worldwide to start a holy war against Russians and Americans, who, according to ISIL, are waging a "crusaders' war" against Muslims, as cited by Reuters.

"We are continuing to continue to pursue the dual tracks that we agreed on in New York with President [Vladimir] Putin," Kerry old a press conference in Boston. "If Russia were to make the right choices… I am convinced [I will] have a profound impact on [the Islamic State] in a much shorter period of time."

Kerry was speaking after participating in a joint ministerial meeting with US defense Secretary Ashton Carter, visiting Australian Foreign Minister Julie Bishop and Defense Minister Marise Payne.

"There is a way to quickly deal with [making progress against the Islamic State] and it involves Russia making a better choice on the political track."

He furthermore claimed the Russian strategy of using air power against Islamist forces in Syria in cooperation with the Syrian government would make Russia an increased target for Islamist extremists.

"They will find they are attracting more jihadis to the fight… So, much hangs in the next weeks as to what choices Russia is prepared to make."

The US government last week tacitly acknowledged its support for the Free Syrian Army had proved to be a fiasco and announced it was going to send military to aid to other groups fighting the Islamic State, and Kerry pledged to step up US efforts to fight the extremists.

"We need to do more. We need to press harder. We need to bring more pressure on [the Islamic State]. The President [Barack Obama] has already made some choices that will increase that pressure."

Also on Tuesday, Russian Foreign Minister Sergei Lavrov said that Washington and its allies in the coalition against the Islamic State must decide whether their aim is to eliminate Islamic State terrorists or to use the extremists to attain political goals.