President Joe Biden united with Washington’s closest allies on Monday to unequivocally condemn Hamas’ deadly attacks on Israel and offer further support to Israel as the country defends itself.

Biden, along with the leaders of France, Germany, Italy and the United Kingdom, wrote that they “​​express our steadfast and united support to the State of Israel, and our unequivocal condemnation of Hamas and its appalling acts of terrorism,” in a rare joint statement. “Our countries will support Israel in its efforts to defend itself and its people against such atrocities.” 

Biden will deliver a public address on the war in Israel on Tuesday afternoon. On Monday night, the White House was illuminated in blue and white in support of Israel.

A senior Department of Defense official outlined American efforts to support Israel in its response to “ISIS level savagery.” 

“We are working as fast as possible to provide critically needed munitions of various types and other equipment,” the official told reporters, and noted that a military “strike group” had been moved to the Eastern Mediterranean. 

“These posture increases were intended to serve as an unequivocal demonstration in deed and not only in words of U.S. support for Israel’s defense and serve as a deterrent signal to Iran, Lebanese Hezbollah, and any other proxy across the region who might be considering exploiting the current situation to escalate conflict,” the Defense Department official said. 

The White House also released further information on Monday about Americans affected by the attacks, although details remained unclear. At least 11 Americans had been confirmed killed in the attacks, and many more were unaccounted for. John Kirby, a spokesperson for the National Security Council, said that the White House was still working to confirm if Americans were indeed among the hostages in Gaza. 

“We are working literally by the hour to try to get more information about these unaccounted for Americans,” Kirby told reporters. “I can’t say definitively that we know that Americans are being held hostage. That said, we have to accept the grim possibility that some are.” Earlier in the day, Kirby teared up in an interview on CNN.

Biden said in another statement that “the safety of American citizens — whether at home or abroad — is my top priority as president.” He shared that he directed American officials to “work with their Israeli counterparts on every aspect of the hostage crisis, including sharing intelligence and deploying experts from across the United States government to consult with and advise Israeli counterparts on hostage recovery efforts.” 

Israeli authorities announced that the death toll passed 900, with 150 people believed to be held hostage by Hamas. 

“This is not some distant tragedy. The ties between Israel and the United States run deep,” Biden said in the Monday statement. “It is personal for so many American families who are feeling the pain of this attack as well as the scars inflicted through millennia of antisemitism and persecution of Jewish people.” 

The strong language from the White House comes as Secretary of State Tony Blinken faced criticism for a tweet in which he called for a ceasefire in Israel. The tweet was deleted on Monday morning, and the State Department and White House declined to comment. Blinken spoke to Israeli Foreign Minister Eli Cohen on Monday. They discussed “U.S. support for Israel as it defends itself against Hamas’ terrorist attacks,” according to the State Department.

Senior White House officials, meanwhile, continued to distance themselves from a bombshell Wall Street Journal report that Iran had orchestrated the Hamas attack.

“No question that there’s a degree of complicity here. Iran has been supporting Hamas for many, many years,” Kirby said. “That said, we haven’t — and we are looking through the information streams — we haven’t seen hard, tangible evidence that Iran was directly involved in participating in, or resourcing or planning these sets of complex attacks that Hamas pulled off over the weekend.”

He noted that “our Israeli counterparts are also actively looking,” and that “even they have publicly said they don’t see the ‘smoking gun.’” Republican members of Congress have attacked the White House for what they view as a weak approach to the Iranian angle in the Hamas attacks. 

“The Biden administration hasn’t acknowledged Iran’s involvement in Hamas’s terrorism because it would be an indictment of the administration’s disastrous concessions to Iran,” Sen. Tom Cotton (R-AR) tweeted on Monday.