The United States will restrict access to American visas for Nigerians taking part in ongoing atrocities against Christians, Secretary of State Marco Rubio announced on Wednesday evening.

“The United States is taking decisive action in response to the mass killings and violence against Christians by radical Islamic terrorists, Fulani ethnic militias, and other violent actors in Nigeria and beyond,” Rubio said.

Boko Haram—which seeks to enforce its radical interpretation of Islamic law in Nigeria and which has targeted Muslims it considers not Muslim enough—as well as terrorist group ISIS West Africa and Fulani ethnic militias have been responsible for a variety of atrocities against Christians in religiously-divided Nigeria, particularly in the northern regions of the state.

These have included mass killings, kidnappings, and the destruction of churches and Christian villages.

Nigerian officials have rejected allegations of widespread Christian persecution, arguing that the Boko Haram group and ISIS West Africa target people of all faiths. Authorities rejected Trump’s past suggestions of possible U.S. military intervention.

Rubio said that the United States intends to respond to the alleged violence by moving to block the visa access of those involved in the perpetration of atrocities against Christians under a provision of the Immigration and Nationality Act that will “allow the State Department to restrict visa issuance to individuals who have directed, authorized, significantly supported, participated in, or carried out violations of religious freedom and, where appropriate, their immediate family members.”

Rubio cited a quote about the issue from President Donald Trump, who said, “The United States cannot stand by while atrocities are happening in Nigeria.”

Last month, Trump also said he had ordered the Pentagon to begin planning a potential military intervention in Nigeria following claims of Christian persecution in the African nation.

The secretary of state added that the new policy “will apply to Nigeria and any other governments or individuals engaged in violations of religious freedom.”

The move comes after the administration last month designated Nigeria as a “country of particular concern” under the International Religious Freedom Act.

Other states currently designated as such include China, Cuba, Eritrea, Iran, Myanmar, North Korea, Nicaragua, Pakistan, Russia, Saudi Arabia, Tajikistan, and Turkmenistan.

Attacks reported in Nigeria have varying motives. Some are religiously motivated, targeting Christians and Muslims alike, depending on the case.

Nigeria’s religious groups are split about evenly between Christians and Muslims in the nation of around 220 million people, which sits along Africa’s western coast facing the Atlantic Ocean.

Other violence in the region stems from clashes between farmers and herders as resources dwindle, as well as rivalries between communities, secessionist militant groups, and ethnic conflicts.