WASHINGTON — Secretary of State John Kerry declared on Thursday that the Islamic State is committing genocide against Christians, Yazidis and Shiite Muslims who have fallen under its control in Syria and Iraq.

The militants, who have also targeted Kurds and other Sunni Muslims, have tried to slaughter whole communities, enslaved captive women and girls for sex, and sought to erase thousands of years of cultural heritage by destroying churches, monasteries and ancient monuments, Mr. Kerry said.

The Islamic State’s “entire worldview is based on eliminating those who do not subscribe to its perverse ideology,” he said.

The statement by Mr. Kerry, made in response to a deadline set last year by Congress for the Obama administration to determine whether the targeting of minority religious and ethnic groups by the Islamic State could be defined as genocide, is unlikely to change American policy. The United States is already leading a coalition that is fighting the militants, and American aircraft have been bombing Islamic State leaders and fighters, its oil-smuggling operations and even warehouses where the group has stockpiled millions of dollars in cash.