WASHINGTON — President Donald Trump said Wednesday that Iran appears to be “standing down” and no Americans or Iraqis were harmed in Iran’s missile strike on two Iraqi bases housing U.S. troops.

Speaking from the White House, Trump seemed intent on deescalating the crisis, indicating that he would not retaliate militarily for the strikes. Instead, he said the U.S. would immediately put in place new economic sanctions “until Iran changes its behavior” after that country’s most brazen direct assault on America since the 1979 seizing of the U.S. Embassy in Tehran.

The attack came days after Trump authorized the targeted killing of Gen. Qassem Soleimani, the head of Iran’s elite Quds Force. Iran had pledged to retaliate, bringing the two countries closer to the brink of war.

Trump credited an early warning system “that worked very well” for the fact that no Americans or Iraqis were killed. He added that Americans should be “extremely grateful and happy” with the outcome.

He reiterated his position that “Iran will never be allowed to have a nuclear weapon” and called for new nuclear negotiations to replace the 2015 nuclear deal from which he withdrew the U.S.

Trump also announced he would ask NATO to become “much more involved in the Middle East process.”

THIS IS A BREAKING NEWS UPDATE. AP’s earlier story follows below.

WASHINGTON — President Donald Trump faces one of the greatest tests of his presidency after Iran launched ballistic missiles at Iraqi bases housing U.S. troops and planned to address the nation on Wednesday. Iran’s attack was its most brazen direct assault on America since the 1979 seizing of the U.S. Embassy in Tehran.

The strikes pushed Tehran and Washington perilously close to war and put the world’s attention on Trump as he weighs whether to respond with more military force. The Republican president huddled with his national security advisers on Wednesday morning but offered no immediate indication of whether he would retaliate. “All is well!” he said in a Tuesday night tweet.

The White House said Trump would speak at 11 a.m. EST.

The Iranian strikes came days after Trump authorized the targeted killing of Gen. Qassem Soleimani, the head of Iran’s elite Quds Force. Iran had pledged to retaliate, though its actions did not appear to result in any American casualties, according to a U.S. official. Its missiles targeted two bases — one in the northern Iraqi city in Irbil and the other at Ain al-Asad in western Iraq.

The lack of U.S. casualties could signal that Iran is not interested in escalating the tension with Washington — at least not now — and could give Trump an opening to calm relations with Iran and pull the U.S. back from the brink of war. Trump, who is facing reelection in November, campaigned for president on a promise to keep the United States from engaging in “endless war.”

Sen. James Inhofe, the chairman of the Senate Armed Services Committee told reporters Wednesday that he spoke with Trump Tuesday evening after the Iranian strike and said the president indicated his desire to reopen negotiations with Iran.

Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin in a joint statement after a closed-door meeting on Mideast security are warning that the further use of force “would lead to a new cycle of instability and would eventually damage everyone’s interests.”

In the hours before the missile strikes, U.S. officials said they expected some sort of response from Iran, and Trump warned the longtime U.S. foe against a disproportionate response. “If Iran does anything that they shouldn’t be doing, they’re going to be suffering the consequences, and very strongly.”

Foreign Minister Mohammad Javad Zarif tweeted that the country had “concluded proportionate measures in self-defense.”

But speaking on Wednesday, Iran’s Supreme Leader Ayatollah Ali Khamenei said the strike was not necessarily the totality of Iran’s response.

“Last night they received a slap,” Khamenei said in a speech. “These military actions are not sufficient (for revenge). What is important is that the corrupt presence of America in this region comes to an end.”

Soleimani’s death last week in an American drone strike in Baghdad prompted angry calls for vengeance and drew massive crowds of Iranians to the streets to mourn him. Khamenei himself wept at the funeral in a sign of his bond with the commander.

The Iranians fired a total of 15 missiles in Wednesday’s strike, two U.S. officials said. Ten hit the Ain al-Asad air base in Iraq’s western Anbar province and one targeted a base in Irbil in Iraq’s semi-autonomous Kurdish region. Four failed, said the officials, who were not authorized to speak publicly about a military operation.

According to a U.S. official, early warning systems detected the missile launches and alarms sounded, giving personnel at the bases time to get to shelter. Officials also said that the U.S. was closely watching the region and communicating with allies, and was aware of preparations for the attack. It’s unclear if any intelligence identified specific targets or was more general in the potential strike locations.

Two Iraqi security officials said a missile appeared to have struck a plane at Ain al-Asad, igniting a fire. There were no immediate reports of casualties from the attacks, according to the officials, who spoke on condition of anonymity as they had no permission to talk to journalists.

Ain al-Asad was first used by American forces after the 2003 U.S.-led invasion that toppled dictator Saddam Hussein, and it later was used by American troops in the fight against the Islamic State group. It houses about 1,500 U.S. and coalition forces. Trump visited it in December 2018, making his first presidential visit to troops in the region. Vice President Mike Pence visited both Ain al-Asad and Irbil in November.

Democrats called on Trump avoid military escalation with Iran.

Rep. Eliot Engel, D-N.Y., the chairman of the House Foreign Affairs Committee, said the administration needs to quickly “extricate us from what could lead into a full-fledged war with terrible casualties.” Engel said he feared the situation ”spirals out of control.”

The fallout for Trump’s order to kill Soleimani has been swift.

Iran announced that it would no longer be bound by the 2015 nuclear agreement and vowed to retaliate against the U.S., its allies and American interests. Iraq’s Parliament also voted to expel U.S. troops from Iraq, which would undermine efforts to fight Islamic State militants in the region and strengthen Iran’s influence in the Mideast.

The counterattack by Iran came as Trump and his top advisers were under pressure to disclose more details about the intelligence that led to the American strike that killed Soleimani.

Top Senate Democrats, citing “deep concern” about the lack of information coming from the Trump administration about the Iran operation, called on Defense Department officials to provide “regular briefings and documents” to Congress.

Minority Leader Chuck Schumer and the senators said in a letter Wednesday that the White House’s classified War Powers notification to Congress was “generic, vague, and entirely inconsistent in its level of detail” compared with the norm.

“While recognizing the need for operations security, we similarly believe there is a requirement to be transparent with the American people about how many troops this Administration plans to deploy in support of contingency plans,” wrote Schumer, Sen. Dick Durbin and the Armed Services Committee’s Sen. Jack Reed to Defense Secretary Mark Esper and Mark Milley, the chairman of the Joint Chiefs of Staff.

They also registered their “grave concern” with Trump’s comments on targeting Iranian cultural sites and asked for clarification. They said they expected a response by Friday.

Trump said Tuesday that his decision saved American lives. Members of Congress were to be briefed on the strike Wednesday afternoon in closed-door sessions on Capitol Hill.

Trump and top national security officials have justified the airstrike with general statements about the threat posed by Soleimani, who commanded proxy forces outside Iran and was responsible for the deaths of American troops in Iraq.

But the details have been scarce.

“He’s no longer a monster. He’s dead,” Trump said. “And that’s a good thing for a lot of countries. He was planning a very big attack and a very bad attack for us and other people, and we stopped him, and I don’t think anybody can complain about it.”

One lawmaker who has read the classified notification that Trump sent Congress after the U.S. air strike that killed Soleimani said the two-page document did not describe any imminent planned attacks or contain any new information. The lawmaker, who spoke on condition of anonymity to describe the classified document, said the letter gave a historic account of attacks that have been reported publicly.

Soleimani was targeted while he was at an airport in Baghdad with Abu Mahdi al-Muhandis, a veteran Iraqi militant, who also was killed.