Saudi Crown Prince Mohammed bin Salman attends the Future Investment Initiative conference last month in Riyadh, Saudi Arabia. (Hamad I Mohammed/Reuters)

Trump administration officials on Tuesday appeared to temper President Trump's wholehearted support of last weekend's purge of domestic rivals by Saudi Arabian Crown Prince Mohammed bin Salman, and issued conflicting statements about a missile attack that the Saudis have blamed on Iran.

Saudi Arabia has said it considers the missile attack an “act of war.” A cabinet meeting Tuesday in Riyadh labeled the strike “an open aggression,” and affirmed “the Kingdom’s right to legitimate defense of its territory,” according to the official Saudi news agency.

The combination of Saudi domestic upheaval and fears of open conflict with Iran left some officials seeking to lower the temperature.

Defense Secretary Jim Mattis, asked if he was concerned that a series of arrests alleging corruption by senior members of the Saudi royal family, officials and business leaders had consolidated national security power in Mohammed’s hands, said he needs more information.

“Let me get back to you on this one, once we’ve settled some back-and-forth sharing of information back to the kingdom,” Mattis told reporters accompanying him on a trip to Brussels.

At the State Department, spokeswoman Heather Nauert said, “We’re continuing to monitor the situation.” The Saudis, she said, “have assured us that any prosecutions that take place will be done in a fair and transparent manner, and we hope that they will hold up to that.”

Trump, on a trip to Asia, had tweeted his support on Monday, saying that some of those under arrest “have been ‘milking’ their country for years.” He said he had “great confidence” in Mohammed and his father, King Salman, and added that “they know exactly what they are doing.”

At the United Nations, U.S. Ambassador Nikki Haley, citing information supplied by Saudi Arabia, accused Iran of supplying one of its newest short-range missiles to Yemeni rebels, and said the United States “will not turn a blind eye to these serious violations of international law by the Iranian regime.”

Saudi officials said Sunday that a missile fired into Saudi Arabia last summer by Houthi rebels in Yemen was an Iranian Qiam, a weapon first tested by Iran in 2010 and one that, Haley said in a statement issued Tuesday, “had not been present in Yemen before the conflict” began there in 2015.

A missile fired last weekend, intercepted by the Saudis near Riyadh's airport, "may also be of Iranian origin," Haley said. She encouraged the United Nations and "international partners" to take unspecified "necessary action to hold the Iranian regime accountable for these violations."

Nauert, at the State Department, declined to respond to what she called a “hypothetical” of possible war with Iran, saying that “we don’t have a full assessment of who is responsible” for the missile attacks. “We haven’t made that determination.”

She also denied that the State Department had received any “heads up” in advance of last weekend’s arrests, but said she was not privy to any conversations that Jared Kushner, Trump’s son-in-law and White House adviser, may have had with Saudi officials during an unannounced visit to Riyadh late last month.

“I have not spoken to Mr. Kushner, nor have I spoken to his office,” Nauert said. Kushner is with Trump on a 12-day trip to Asia.

Kushner has formed a close relationship with the 31-year-old Saudi crown prince and played a leading role in organizing Trump’s visit to Riyadh on his first overseas trip last summer. “Those two peas in a pod,” a former State Department official familiar with administration policy in the region said of the two sons of political and financial power.

The former official, speaking on the condition of anonymity to offer a candid assessment, said that policy officials outside the White House have been concerned that Kushner, whose primary experience and interest in the region is Israel, is ill-prepared for the Middle East’s complicated dynamics.

While some outside experts have speculated that Kushner and Mohammed may have discussed the prince’s plans for a domestic crackdown during last month’s visit, the Saudis, the former official said, “don’t need a green light” from the White House for actions such as the wave of weekend arrests. “They’re going to expect the White House is going to stand behind them and support them.”

Since Trump’s visit, it is the president who has been most publicly adulatory in his praise for Salman. But he wasn’t always so complimentary.

Over the years, Trump has criticized U.S. military support for Saudi Arabia, which he said wasn’t paying enough for the protection. “The Saudi government would be overthrown in about 15 seconds if we weren’t protecting Saudi Arabia,” he said in a Playboy interview in 2004. Four years later, Trump called former president George W. Bush “stupid” because he “goes to Saudi Arabia and wraps his arms around these people and says, you know, ‘we love you, we love you.’ ”

But Trump, who said after his Saudi trip that he would not have gone unless the kingdom promised major U.S. defense purchases and investment deals, has touted an agreement by Saudi Arabia, long the top purchaser of American weapons, to buy $110 billion more.

In addition to seeking Saudi money and assistance in the peace process, the administration clearly considers Saudi Arabia a key player in its still-unformed plans to stem Iranian influence.

Mohammed and his growing power provokes mixed feelings. On one hand, reforms he has pushed, including rapid diversification from the kingdom's oil economy and the loosening of cultural and religious restrictions, have met with widespread domestic and international favor. Rumors surface regularly that his father will imminently turn over complete power to him, although that is considered unlikely before Salman makes a promised visit to the United States in the first half of next year.

Yemen’s Houthi rebels attract little sympathy in their battle to take over that country, and there is little doubt that much of their success in holding their own against the Saudis is due to Iranian assistance.

But concern about how Mohammed — who also serves as defense minister — is running the Saudi side of the war is growing along with his power.

“How much faith do we want to put into a 31-year-old guy who’s really focused on his domestic situation?” said the former official. “Are we going to let him provoke a crisis in the region?

Michael Kranish contributed to this report.