US President Joe Biden said on Saturday he told Israeli Prime Minister Benjamin Netanyahu that the United States was ready to offer "all appropriate means of support " after Palestinian movement Hamas launched an attack on Israel.
"I made clear to Prime Minister Netanyahu that we stand ready to offer all appropriate means of support to the Government and people of Israel," Biden said in a statement after he spoke with Netanyahu.
"Israel has a right to defend itself and its people. The United States warns against any other party hostile to Israel seeking advantage in this situation," he added.
Earlier, a White House National Security Council spokesperson said the US "unequivocally condemns" attacks by Hamas against Israeli civilians and firmly stands with the government and people of Israel, CNN reported on Saturday.
Citing a statement from the spokesperson, CNN reported that White House National Security Adviser Jake Sullivan had spoken with his Israeli counterpart, Tzachi Hanegbi, and would remain in close contact.
Britain "unequivocally condemns" a surprise attack by Palestinian movement Hamas on Israel, Foreign Secretary James Cleverly said.
"The UK unequivocally condemns the horrific attacks by Hamas on Israeli civilians. The UK will always support Israel’s right to defend itself," Cleverly said in a post on social media.
British Prime Minister Rishi Sunak said he was shocked by the attacks.
"We're in contact with Israeli authorities, and British nationals in Israel should follow travel advice," Sunak added.
French President Emmanuel Macron said he strongly condemned the attacks.
"I strongly condemn the terrorist attacks which are currently hitting Israel. I express my full solidarity with the victims, and their families and those close to them," Macron wrote on X.
The French foreign ministry said earlier that Paris condemned the "terrorist attacks under way against Israel and its population" and that it expressed its full solidarity with Israel.
German Foreign Minister Annalena Baerbock said she strongly condemned the attacks, saying violence against innocent people must stop straight away.
"I strongly condemn the terrorist attacks against Israel from Gaza. Violence and rockets against innocent civilians must stop now. We stand in full solidarity with Israel and its right under international law to defend itself against terror," Baerbock said on X.
Ukraine's foreign ministry condemned what it described as "ongoing terrorist attacks" on Israel.
"Ukraine strongly condemns the ongoing terrorist attacks against Israel, including rocket attacks against the civilian population in Jerusalem and Tel Aviv," the ministry said on X.
"We express our support for Israel in its right to defend itself and its people."
Hamas launched the biggest attack on Israel in years on Saturday, killing dozens of people and taking hostages in a surprise assault that combined gunmen crossing into Israel with a barrage of rockets fired from the Gaza Strip.
Israel said the Iran-backed group had declared war as its army confirmed fighting with militants in several Israeli towns and military bases near Gaza, and Netanyahu vowed to retaliate.
"Our enemy will pay a price the type of which it has never known," he said. "We are in a war and we will win it".
Israel's N12 News reported that at least 100 Israelis were killed. A Reuters photographer saw multiple bodies lying in streets of the southern town of Sderot.
Gaza health officials said 198 Palestinians had been killed in air strikes as bombardments hit deep into Gaza City, sending clouds of black smoke spiraling into the sky.
Hamas military commander Mohammad Deif announced the start of the operation in a broadcast on Hamas media, calling on Palestinians everywhere to fight.
"This is the day of the greatest battle to end the last occupation on earth," he said, adding that 5,000 rockets had been launched.
The last major flare-up between Israel and Hamas was a 10-day war in 2021.