There is a popular saying about Apple's new products: When Apple founder Steve Jobs was at the helm of affairs, people knew nothing but the name of a new product before it hit the market, after Tim Cook took over the reins, people know all but the name of a product before its launch.

To some extent, US President Barack Obama is like Cook in his belated "new" move against the "Islamic State", formerly known as the Islamic State of Iraq and Syria (or the Levante). Delivering a speech on the eve of the 13th anniversary of the Sept 11, 2001, attacks, Obama reiterated that Washington will mainly use its air power and international allies' assistance to help Iraqi and Kurdish forces fight the IS, and that US troops will not be on the frontline.

Nothing that Obama said about the IS, which occupies swaths of land in northern Iraq and Syria, is new. And anyway, its military strategy is not likely to eliminate the IS within three years as Obama has claimed, because of a fatal strategic flaw, which is the US' insistence on targeting the Syrian government led by President Bashar al-Assad, the only regional leader willing and able to take on the Islamic militants with full military force.

Since the IS occupies territories both in Iraq and Syria, any military action against the group has to cover both countries in order to be successful. In other words, there has to be continuity in the military operation. But since Syrian troops cannot cross over into Iraqi territory, the battle against the IS has to be fought on two fronts.

After Syria launched an attack on the IS, most of its members fled to Iraq. Now that Iraqi and Kurdish forces - supported by US-led air strikes - are pursuing them, the IS extremists are most likely to retreat into Syria. That means the US has two choices: It could either block the fleeing extremists' access to Syria and launch a joint operation with Syrian forces to corner them, or just watch from the sidelines the tug of war between Damascus and the remaining IS terrorists in Syria.

Unfortunately but almost undoubtedly, the US will do neither going by Obama's latest remarks reiterating that the Assad government is "illegal". Worse, the US has promised to redouble its military support to the "moderate opposition" to Damascus and launch air strikes on IS extremists in Syria with or without the Assad's permission.

If Obama indeed puts his words into action, there is a high possibility that the Syrian army, too, will come under direct US attack. And if that eventually happens, the US would want to see the end of both Assad and Abu Bakr al-Baghdadi, the self-proclaimed khalifah of the IS.

But the problem is that the elimination of the IS and overthrow of Assad cannot be done simultaneously, not by the powerless moderate Syrian rebel groups even if they are funded by the US. Without US military intervention in Syria, and a mighty one at that, the moderate rebels will not stand a chance in the trilateral fight over the control of the country - a point that has been repeatedly proved on the Syrian battlefield.

Therefore, to eliminate the cold-blooded IS, Washington has to acknowledge the "legitimacy" of the Assad government and accept it as a "partner" in the fight against the Islamic extremists. If not, it could only watch the IS make fresh inroads into Syria or, worse, even seize power from Assad if he is weakened fighting the rebels and the IS on two fronts. Such being the case, why on earth would the US try to take both "enemies" out at the same time?

The author is a researcher in South Asian studies at the Chinese Academy of Social Sciences.