DUBAI, United Arab Emirates — The nationwide protests challenging Iran’s theocracy appeared increasingly smothered Thursday, a week after authorities shut the country off from the world and escalated a bloody crackdown that activists say has killed at least 2,637 people. The prospect of U.S. retaliation for the protesters' deaths still hung over the region, though President Donald Trump signaled a possible de-escalation, saying the killing appeared to be ending. The White House stressed that “all options remain on the table.” Meanwhile, the U.S. announced new sanctions on Iranian officials accused of suppressing the protests, which began late last month over the country's faltering economy and the collapse of its currency. The Group of Seven industrialized democracies and the European Union said they too were looking at new sanctions to ratchet up the pressure on Iran's theocratic government. The U.N. Security Council scheduled an emergency meeting on Iran for Thursday afternoon at the request of the United States. In Iran's capital, Tehran, witnesses said recent mornings showed