The U.S. military said on Sunday it will not reveal specific details about its military strikes in Yemen, citing what it called the need "to preserve operational security" while also saying the strikes had "lethal effects" on Houthi rebels.

President Donald Trump ordered the intensification of U.S. strikes on Yemen last month, with his administration saying it will continue assaulting Iran-backed Houthi rebels until they stop attacking Red Sea shipping.

Recent U.S. strikes have killed dozens, including 74 at an oil terminal in mid-April in what was the deadliest strike in Yemen under Trump so far, according to the Houthi-run health ministry.

Rights advocates have raised concerns about civilian killings and three Democrat senators, including Senator Chris Van Hollen of Maryland, wrote to Pentagon chief Pete Hegseth on Thursday demanding accounting for loss of civilian lives. Hegseth has also come under fire for using the unclassified messaging system Signal to discuss Yemen attack plans.

"To preserve operational security, we have intentionally limited disclosing details of our ongoing or future operations. We are very deliberate in our operational approach, but will not reveal specifics about what we've done or what we will do," the U.S. Central Command said in a statement.

The military said it has struck over 800 targets since mid-March that it says killed hundreds of Houthi fighters and numerous Houthi leaders as well as destroyed the militant group's facilities.

Washington says the strikes aim to cut off Houthi military and economic capabilities while minimizing civilian harm.

It said on Thursday that an April 20 blast near a UNESCO world heritage site in Yemen's capital Sanaa was caused by a Houthi missile and not an American airstrike. The Houthis said a dozen people were killed in that incident and dismissed the U.S. denial.

The Houthis have taken control of swathes of Yemen over the past decade.

Since November 2023, they have launched attacks on vessels in the Red Sea, saying they were targeting ships linked to Israel.

They say they are acting in solidarity with Palestinians in Gaza where Israel's war has killed over 51,000, according to Gaza's health ministry, and devastated the coastal enclave. The latest bloodshed in the Israeli-Palestinian conflict was triggered by Hamas militants attacking Israel in October 2023, when they killed 1,200 people and took about 250 hostages, according to Israel.