Washington, September 16 (RHC)-- The U.S. military is preparing a response to the recent Yemeni drone attacks on Saudi Arabia's oil facilities, Defense Secretary Mark Esper has said.

Esper briefed U.S. President Donald Trump in the White House on Monday following the attacks on two Saudi Aramco oil facilities on Saturday that knocked out more than half the kingdom’s production.   

Yemen's Houthi fighters have claimed responsibility for the attack, but the United States has rejected their claim with Trump saying that Iran appears to be responsible for the strike.

Esper did not directly put blame on Iran for the attack but accused it of undermining international order.  "The United States military, with our inter-agency team, is working with our partners to address this unprecedented attack and defend the international rules-based order that is being undermined by Iran," he said in a tweet.

Esper said he and the Pentagon leadership met with Trump in the wake of Saturday's attack.  Following a briefing from his military and intelligence advisers at the White House on Monday, Trump was asked whether Iran was behind the attack, Trump said: "It's certainly looking that way at this moment and we'll let you know.  As soon as we find out definitively we'll let you know but it does look that way."

A day earlier, Trump said the United States was “locked and loaded” for a possible response to the attacks on Saudi Arabia's oil facilities.  Trump said that Washington has a "reason to believe that we know" who is responsible for the attacks carried out against the kingdom’s key oil facilities in Abqaiq and Khurais on Saturday.

U.S. Secretary of State Mike Pompeo put the blame for the operation on Iran, claiming: “Tehran is behind nearly 100 attacks on Saudi Arabia” and that “there is no evidence the attacks came from Yemen.”

Tehran, however, dismissed the allegation, saying Washington seems to be shifting from a failed campaign of “maximum pressure” to one of “maximum lying” and “deceit” against the Islamic Republic.