, April 13 -- Andreas Krieg, a senior lecturer in security studies at Kings College London, said Sunday that Trump's plan to use the U.S. Navy to block the Strait of Hormuz is unrealistic.

"We should bear in mind that the Americans have a much lower threshold of pain than the Iranians," Krieg said. "The Iranians, whatever happens, can sustain this for far longer than the world economy, far longer the Gulf states, far longer then the Americans."

Krieg said Trump doesn't have "any good options" and that he will have to concede on some issues.

"There isn't any tool in the toolbox in terms of the military lever that he could use to get his way," he said.

Earlier, President Donald Trump said the U.S. Navy would swiftly begin a blockade of ...