The US secretary of state, Antony Blinken, has said the attacks by Hamas on Israel on Saturday had “harrowing echoes” of Nazi massacres, as he stood alongside the Israeli prime minister, Benjamin Netanyahu, in Jerusalem in an act of public solidarity. Blinken, who is Jewish, vowed that the US would stand for ever alongside Israel, and said he would use his tour of the region to urge all parties, especially Hezbollah, not to broaden the conflict or open a second front. Meanwhile, Syria said the runways at its airports in Damascus and Aleppo had been bombed by the Israeli air force, the first time Israel has hit Syria since Saturday’s attacks. At a press conference in Tel Aviv, Blinken told Israelis: “You may be strong enough on your own to defend yourself. But as long as America exists, you will never, ever have to. We will always be there by your side.” He said at least 25 Americans were killed in the Hamas attacks and he promised there was overwhelming bipartisan support in Congress to supply Israel with whatever weaponry it needed. Insisting this must be a moment for moral clarity, Blinken said Palestinians had legitimate aspirations but they were not represented by Hamas. He is due to meet the leader of the Palestinian Authority, Mahmoud Abbas, in the West Bank on Friday. “Anyone who wants peace and justice must condemn Hamas’s reign of terror,” he said. “We know Hamas doesn’t represent the Palestinian people or their legitimate aspirations to live with equal measures of security, freedom, justice, opportunity and dignity.” Blinken said: “I come before you not only as the United States secretary of state but also as a Jew. I understand on a personal level the harrowing echoes that Hamas’s massacres carry for Israeli Jews and for Jews everywhere. “It’s impossible for me to look at the photos of families killed, such as the mother, father and three small children murdered as they sheltered in their home in kibbutz Nir Oz, and not think of my own children.” Joe Biden had initially appeared to give Israel a blank cheque in how it pursued its plan to cleanse Gaza of Hamas, but later US officials stressed that Israel needed to conduct the war in line with international law, including by acting proportionately and protecting civilians. Iran has already accused Israel of committing a genocide. Israel appears divided over how to pursue the aerial bombardment in Gaza, especially as there are more than 100 hostages being held by Hamas. Qatar and Turkey have been leading talks about a prisoner swap, initially involving women and children. Blinken will be seeking an Israeli assessment of its planned land invasion designed to degrade and destroy Hamas military leadership. It is widely accepted that Israel intends to go further than the 11-day incursion into Gaza in May 2021, the fourth such incursion since Israel left Gaza in 2005. Standing beside Blinken, Netanyahu said: “Thank you, America, for standing with Israel, today, tomorrow and always.” Netanyahu, who has had strained relations with Biden, praised the US president for his remarks on Wednesday calling the Hamas attacks “sheer evil”. Biden also noted that the attacks were “the deadliest day for Jews since the Holocaust”. “Just as Isis was crushed, so too will Hamas be crushed,” Netanyahu said. “And Hamas should be treated exactly the way Isis was treated.” Although the chances of diplomacy making much progress in the current climate seem slim, Blinken will be hoping that if Hezbollah and Iran are persuaded to avoid escalating the conflict, and Hamas is severely damaged militarily, it may be possible to persuade Israel that the status quo is not tenable and it must listen to Saudi Arabia’s call for Israel to talk with Palestine about a two-state solution. Netanyahu has shown no interest in such a step. The US will do nothing to weaken Netanyahu at present but he will be under growing domestic pressure to explain the intelligence failure that led to the Hamas assault being so devastating. The Israeli leader has been forced to form a national unity government and US officials will be watching to see if this means he is willing to become less dependent on the extremist rightwing members of his own government.