President Barack Obama has approved surveillance flights over Syria to gain information on Islamic State militants.
The flights, which are reported to have commenced on Tuesday, are widely seen as a precursor for expanding the range of US airstrikes on IS positions in Iraq into Syria, according to The Guardian.
US officials ruled out cooperating with the Syrian government on fighting IS.
“It is not the case that the enemy of my enemy is my friend,” said Benjamin J. Rhodes, a deputy national security adviser to the New York Times.
“Joining forces with Assad would essentially permanently alienate the Sunni population in both Syria and Iraq, who are necessary to dislodging [IS].”
Syria on Monday offered to help the US in its fight against IS.