DUBAI, United Arab Emirates — Iran’s bloody crackdown on nationwide protests has killed at least 6,221 people while many others still are feared dead, activists said Wednesday, as a U.S. aircraft carrier group arrived in the Middle East to lead any American military response to the crisis. Iran’s currency, the rial, meanwhile fell to a record low of 1.5 million to $1.

The arrival of the USS Abraham Lincoln aircraft carrier and guided missile destroyers accompanying it provide the U.S. the ability to strike Iran, particularly as Gulf Arab states have signaled they want to stay out of any attack despite hosting American military personnel.

Two Iranian-backed militias in the Mideast have signaled their willingness to launch new attacks, likely trying to back Iran after U.S. President Donald Trump threatened military action over the killing of peaceful protesters or Tehran launching mass executions in the wake of the demonstrations.

Iran has repeatedly threatened to drag the entire Mideast into a war, though its air defenses and military are still reeling after the June war launched by Israel against the country. But the pressure on its economy may spark new unrest as everyday goods slowly go out of reach of its people — particularly if Trump chooses to attack.

Ambrey, a private security firm, issued a notice Tuesday saying it assessed that the U.S. “has positioned sufficient military capability to conduct kinetic operations against Iran while maintaining the ability to defend itself and regional allies from reciprocal action.”

“Supporting or avenging Iranian protesters in punitive strikes is assessed as insufficient justification for sustained military conflict,” Ambrey wrote. “However, alternative objectives, such as the degradation of Iranian military capabilities, may increase the likelihood of limited U.S. intervention.”

Wednesday’s new figures came from the U.S.-based Human Rights Activists News Agency, which has been accurate in multiple rounds of unrest in Iran. The group verifies each death with a network of activists on the ground in Iran.

It said the 6,221 dead included at least 5,858 protesters, 214 government-affiliated forces, 100 children and 49 civilians who weren’t demonstrating. The crackdown has seen over 42,300 arrests, it added.