WASHINGTON (AP) — President Barack Obama's chemical weapons position on Syria may have given Bashar Assad an unintended opening: The embattled Syrian leader appears willing to use other deadly tactics, including Scud missiles, without fear of U.S. retaliation.

The White House casts Assad's escalation against rebel forces as a sign of his growing desperation as his opposition gets stronger and enjoys more international support, including from the United States. But some human rights groups and Middle East experts say Obama's "red line" has given Assad a green light to launch attacks on his own people through other conventional means.

Obama has said Syria's use or movement of its chemical weapons stockpile would change his "calculus" about a conflict the U.S. has been loath to intervene in militarily.