U..S Secretary of State Marco Rubio on Sunday condemned the "radical Islamist terrorists" behind "massacres" of minorities in Syria and demanded that the interim administration hold those responsible to account.

"The United States condemns the radical Islamist terrorists, including foreign jihadis, that murdered people in western Syria in recent days," Rubio said in a statement.

"The United States stands with Syria's religious and ethnic minorities, including its Christian, Druze, Alawite, and Kurdish communities, and offers its condolences to the victims and their families," he said.

"Syria's interim authorities must hold the perpetrators of these massacres against Syria's minority communities accountable."

The violence against minorities erupted after gunmen loyal to ousted leader Bashar al-Assad, a member of the Alawite minority, attacked the new security forces.

War monitor the Syrian Observatory for Human Rights later reported that security forces and allied groups killed at least 745 Alawite civilians in Latakia and Tartus provinces.

Interim President Ahmad al-Sharaa, who led the Sunni Islamist group Hayat Tahrir al-Sham that spearheaded the lightning offensive that toppled Assad, called for national coexistence after the killings.

The United States under former president Joe Biden engaged with Sharaa after he came to power but said that any greater normalization would depend on meeting conditions including the protection of minorities.

Donald Trump, then president-elect, said at the time that the United States had little interest in Syria and should stay out, and he has previously spoken of removing U.S. troops in the country to fight the Islamic State movement.

Since taking office, the Trump administration has said little about Syria but has severely slashed assistance to groups assisting civilians in the war-ravaged country.

The United States did not join Britain on Thursday in announcing an easing of Assad-era sanctions on Syria.