The harsh effects of Trump's Iran sanctions, and why Iranians worry the worst is still to come

In the days since some U.S. sanctions on Iran snapped back into place, the signs of misery have been everywhere in Tehran's commercial districts.

Stores are open but empty. Shopkeepers pass the time on their cellphones and exchange tales of economic woe: prices soaring, workers laid off, inventory going stale.

President Donald Trump has said his goal is to place "maximum economic pressure" on a country he accuses of fomenting instability and backing U.S. adversaries across the Middle East.

But many Iranians believe the Trump administration wants to topple the theocracy in place since the 1979 Islamic Revolution - a risky policy that Iran's deeply entrenched clerical establishment has many ways to survive.

Meanwhile, the sanctions