WASHINGTON • President Donald Trump vowed on Tuesday to remain a steadfast partner of Saudi Arabia despite saying that Saudi Crown Prince Mohammed bin Salman may have known about the plan to murder journalist Jamal Khashoggi.

Defying intense pressure from US lawmakers to impose tougher sanctions on Saudi Arabia, Mr Trump also said he would not cancel military contracts with the kingdom. He said it would be a foolish move that would only benefit Russia and China, competitors of the United States in the arms market.

Mr Trump said US intelligence agencies are still studying the evidence surrounding Mr Khashoggi's killing inside the Saudi consulate in Istanbul and who planned it. Since the Oct 2 murder, Mr Trump has taken varying positions on how to react, including possible sanctions.

But on Tuesday, Mr Trump stressed Saudi Arabia's weapons purchases and its role in keeping world oil prices low as influencing his decision.

"It is all about, for me, very simple. It is America first," Mr Trump said, adding: "I am not going to destroy the world economy and I am not going to destroy the economy for our country by being foolish with Saudi Arabia."

Punishing Saudi Arabia, Mr Trump said, would put at risk US$110 billion (S$151 billion) in military sales to Boeing, Lockheed Martin, Raytheon and other military contractors as well as US$340 billion in other investments, which the Saudis have agreed to make since he became president.

Speaking at the White House to reporters before departing for Florida, Mr Trump said of the possibility that the Saudi Crown Prince had a hand in the murder: "Maybe he did, maybe he didn't."

He also argued that the Central Intelligence Agency (CIA) had not made a definitive determination.

His comments contradicted the CIA, which believes that Mr Khashoggi's death was ordered directly by the Crown Prince, Saudi Arabia's de facto ruler.

Mr Trump was accused by Democratic lawmakers of undermining his own intelligence agencies and failing to confront Saudi Arabia over a human rights atrocity.

Democratic and Republican lawmakers have urged Mr Trump to drop his support for Prince Mohammed over the Khashoggi case, but the President has been reluctant to do so.

Mr Trump said on Tuesday that both Saudi Arabia's King Salman and Prince Mohammed "vigorously deny any knowledge of the planning or execution of the murder", and that the truth may never be known.

After offering numerous contradictory explanations for the disappearance of Mr Khashoggi, Riyadh said last week that he had been killed and his body dismembered when negotiations to convince him to return to Saudi Arabia failed. It said allegations that the Crown Prince had ordered the killing were false.

Turkish Foreign Minister Mevlut Cavusoglu said in Washington on Tuesday that Turkey was not entirely satisfied with the level of cooperation it was receiving from Riyadh on Mr Khashoggi's murder and may seek a formal United Nations inquiry.

Republican and Democratic leaders of the US Senate Foreign Relations Committee said they had asked Mr Trump for a second human rights probe over the killing of the journalist.

Similarly, Representative Francis Rooney, a Republican on the House Foreign Affairs Committee, said Washington should apply the Magnitsky Act to those responsible for Mr Khashoggi's death. The law freezes US assets of human rights violators and prohibits Americans from doing business with them.

Mr Trump said Saudi Arabia, a major oil producer, was an important business partner and a great ally in the fight against Iranian power in the Middle East.

"The United States intends to remain a steadfast partner of Saudi Arabia to ensure the interests of our country, Israel and all other partners in the region," Mr Trump said.

On Twitter, Iranian Foreign Minister Mohammad Javad Zarif said: "Mr Trump bizarrely devotes the first paragraph of his shameful statement on Saudi atrocities to accuse Iran of every sort of malfeasance he can think of."

Mr Khashoggi, a critic of the Saudi government, lived in the US and was a Washington Post columnist. He went to the consulate to collect documents for a planned marriage.

Mr Trump has placed the alliance with Saudi Arabia at the heart of his Middle East policy, and it was the first country he visited after becoming president last year.

NYTIMES, REUTERS