And our reporters learned that the Kurdish militia, angered by the U.S. military withdrawal before the assault, blocked the Americans from extracting about five dozen “high value” Islamic State detainees from the prisons the militia runs. Here’s an explainer on the prisons, which hold about 11,000 men.

ISIS has already claimed responsibility for at least two attacks since the start of the invasion.

Further U.S. withdrawal: The U.S. said it would withdraw about 1,000 of its remaining troops from northeastern Syria, effectively ceding control to the Syrian government and Russia. Green Berets described feeling “ashamed” at orders to abandon their Kurdish allies.

Russia’s Syria role: Our video investigation proves that the Russian Air Force repeatedly bombed hospitals in rebel-held areas of Syria to crush remaining resistance to the country’s president, Bashar al-Assad.

Analysis: President Trump’s abrupt shift in Syria and acquiescence to the Turkish invasion have alarmed America’s allies in the Middle East.