Israel has opened a new phase in its war on Hamas by expanding ground operations inside Gaza, but analysts warn the campaign is its riskiest in half a century with fallout threatening the whole Middle East.

According to AFP, that adds to Western fears that Iran-backed Hezbollah could open a new front on the Lebanese border. Officials say Israel does not want to stay in Gaza and there are also concerns over who will administer the territory and pay for its reconstruction after the guns fall silent.

“We are going to see a lot of carnage, we are going to see a lot of horrible things,” said Edward Djerejian, a former US assistant secretary of state and ambassador to Israel, who bemoaned the lack of a political initiative to end the crisis.

This showdown is Israel’s most perilous since the 1973 Arab-Israel war, when it was also taken by surprise, according to Jonathan Rynhold, a specialist on the Israel-Palestinian conflict at Bar-Ilan University near Tel Aviv.

He said Israel will have to be ready for major casualties which will be worse if Hezbollah turns its near-daily artillery exchanges with Israel into all-out conflict.

“If Israel follows through on the stated aim of destroying Hamas military capabilities in the Gaza Strip and overthrowing its regime, then the scale and length of this war will be much bigger and much longer” than the four previous Gaza wars since 2005, the longest of which lasted seven weeks, said Rynhold.

The expansion of ground of operations “will be the critical moment as to whether a second front opens with Hezbollah and that is a higher risk” than in previous wars, he added.

Open conflict with Hezbollah could drag in the United States and would mean Israel having to accept “a scale of destruction that it has never experienced before,” Rynhold said.

H A Hellyer, a security specialist for the Royal United Services Institute in London, said that Israel is not doing enough to head off new war fronts.

“There is a risk of extension of the conflict,” he said. “Israel is prioritising revenge and retaliation over all else, as far as we can see from the statements of senior Israeli officials.”

Khalil Shikaki, director of the Palestinian Center for Policy and Survey Research in Ramallah, said Hamas is “probably a lot more popular today” in the Arab region than before the attacks.

Hamas will retain significant influence in Gaza after the war, he predicted.

Israel’s reputation “depends on its projection of strength, its swagger,” said Laura Blumenfeld, a former US State Department adviser on Israel-Palestinian negotiations and now a security specialist at Johns Hopkins University.

If the war tarnishes “its sheen of deterrence” it will look “weak” before its rivals and countries that might be considering normalising ties, she added.