Explainer-What are Iran's options to escalate further in face of US economic threats?

LONDON, Aug 24 - U.S. threats to impose "the toughest sanctions in history" to force Iran to buckle to its demands after nearly six months of war have raised the prospect of a new round of escalation in the Gulf. How could Iran respond to the economic pressure? CAN IRAN STOP MORE OIL GETTING OUT OF THE MIDDLE EAST? Mohsen Rezaei, the former Revolutionary Guards chief and secretary of Iran's Supreme National Security Council, has already threatened to shut down oil exports — one of Tehran's main…