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In his first remarks on the war, the king repeated his call for an independent Palestinian state, one of Jordan's major foreign policy planks. A large proportion of Jordan's 10 million citizens are descendants of Palestinians who fled the creation of Israel in 1948 and its expansion in the 1967 Middle East war.
The king told parliament that the "dangerous escalation" in Palestine proves "that our region will never be secure nor stable without achieving just and comprehensive peace on the basis of the two-state solution".
The war began at the weekend after the Hamas militant group attacked Israeli-controlled areas near Gaza, killing hundreds of people, mostly non-combatants.
It has forced Jordanian authorities into a balancing act aimed at placating street anger at Israel's overwhelming show of force in response, while maintaining the kingdom's external alliances.
On Tuesday night, thousands of people marched in a rally in downtown Amman, led by the Muslim Brotherhood which, unlike with other Arab governments, is tolerated in Jordan.
Marchers raised Palestinian flags and shouted slogans demanding the authorities allow people to go fight against Israel, across the border.
Jordanian Prof Hasan Al Momani said authorities were seeking to provide a "ventilation valve" for popular sentiment about the war, while playing a role as an interlocuter in the crisis.
Prof Al Momani said US Secretary of State Antony Blinken would make Amman his second and only other stop in the region after he visits Israel on Thursday.
"The Palestinian cause, as the key to the security of the region, is an internal, as well as an external priority for Jordan," said Prof Al Momani, who heads the International Relations and Regional Studies Department at the University of Jordan.
"The king was clear about the consequences of not resolving it," he said.
The kingdom, a US ally dependent on western aid, has a peace treaty and security ties with Israel. Jordanian officials in Amman have long feared what they describe as Jordan becoming an "alternative state", if Israeli pressure results in another wave of refugees to the kingdom.
The authorities have also maintained security channels with Hamas, although King Abdullah expelled the group's leadership from the country in the late 1990s.
The State Department said Mr Blinken will go to Israel and Jordan from October 11 to 13, where he will discuss bolstering Israel’s security and unwavering US support for Israel’s right to self defence.
"The secretary will reiterate his condolences for the victims of the terrorist attacks against Israel and condemn those attacks in the strongest terms," an official US statement said.