The White House has issued additional information about its claim that the Syrian government was preparing for a possible chemical weapons attack. On Tuesday, Pentagon spokesperson Captain Jeff Davis said the U.S. had recently observed activity at Shayrat airfield—the same airbase from which the U.S. and human rights groups say the Syrian government allegedly carried out a chemical weapons attack in April that killed 86 people in the town of Khan Sheikhoun. Spokesperson Davis said the activity “involved specific aircraft in a specific hangar, both of which we know to be associated with chemical weapons use.”

However, the White House faced continued skepticism from the intelligence community Tuesday about the claims, as well as about the release of the White House statement Monday warning Assad of retaliation in the event of a chemical weapons attack. Five unnamed military officials told BuzzFeed they did not know about the intelligence before the statement’s release or that the White House was even preparing to release a statement. The statement appears to be aimed at drumming up American public support for an upcoming U.S. military strike against the Syrian government.

Both the Syrian and Russian governments have rejected the White House’s claims.