White House spokesman Jen Psaki welcomed the resumption of Syrian-Jordanian flights at a news conference on Tuesday.
But he told reporters by telephone an hour later that he would step down and that Washington would look into the matter.
Extensive, two-day meetings between Jordanian and Syrian officials in Amman ended on Tuesday, at the end of which several decisions were agreed upon by the two sides, including the resumption of Jordanian flights to Syria from October 3rd.
Flights between Jordan and Syria have been suspended since 2012.