They are images that will infuriate the Palestinian leadership: the Israeli prime minister, Benjamin Netanyahu, smiling and joking with Arab leaders at an international conference on the Middle East.

Israel has formal diplomatic relations with only two Arab states, Egypt and Jordan. For decades, one price the country has paid for its occupation of the Palestinian territories has been snubs by the majority of its neighbours.

Events at a two-day summit in Warsaw, however, tell a different story. First there were the videos of Netanyahu sitting with Arab officials at the grand opening dinner on Wednesday night.

“I believe we are beginning a new era,” the US vice-president, Mike Pence, said at the meal. “With prime minister Netanyahu from the state of Israel, with leaders from Bahrain, Saudi Arabia and the UAE all breaking bread together.”

Then there was the meeting and warm handshake with the Omani foreign minister, Yusuf bin Alawi bin Abdullah. It built on another landmark trip Netanyahu made in October when he met with the Gulf country’s sultan, the first such visit in more than two decades.

PM @Netanyahu met with Omani FM Yusuf bin Alawi bin Abdullah in Warsaw: “The courageous decision of Sultan Qaboos to invite me to #Oman is changing the world. It’s pointing the way for many others to do what you said - not to be stuck in the past but to cease the future.” pic.twitter.com/20JolijILO — Raphael Ahren (@RaphaelAhren) February 13, 2019

The gut-punch, though, was a brief smile with the foreign minister of Yemen, whom Netanyahu sat next to for a group discussion. Jason Greenblatt, Donald Trump’s Middle East envoy, said Khaled Alyemany had even offered Netanyahu his microphone when the Israeli premier’s broke during a closed session. “Netanyahu joked about the new cooperation between Israel and Yemen. Step by step ... ” Greenblatt tweeted.

The Israeli leader, who is likely to become the country’s longest-serving prime minister if he wins the forthcoming election in April, has promised his citizens that warmer ties with Arab states are still possible despite lacklustre peace efforts with the Palestinians.

Antipathy toward Iran and trade are two areas where his government has sought to find common ground, hoping they will overshadow Arab solidarity with the Palestinians, who have long relied on regional pressure against Israel.

“In a room of some 60 foreign ministers representative of dozens of governments, an Israeli prime minister and the foreign ministers of the leading Arab countries stood together and spoke with unusual force, clarity and unity against the common threat of the Iranian regime,” Netanyahu told reporters in Warsaw.

Arab countries have been reluctant so far to show public ties, fearful of domestic embarrassment, but there are growing signs of thawing relations. Saudi Arabia opened its airspace to an Israel-bound passenger plane last March, breaking a 70-year-ban on commercial jets flying over the kingdom to reach the Jewish state.

Washington has also pressured Arab leaders, seeking their backing in an unreleased peace plan drafted by Trump’s son-in-law, Jared Kushner. His deal is rumoured to reward Israel with normalised relations with some Middle East powers in return for yet-to-be-specified compromises for the Palestinians.

A Palestinian delegation was reportedly invited to the conference, but refused to attend. The West Bank-based leadership rejected Washington’s historical role as a peace mediator after Trump declared the contested city of Jerusalem as Israel’s capital.

“Palestine will not provide cover to warmongering or legitimise efforts to market an Israeli-centric fake solution that normalises Arab-Israeli relations at the expense of Palestinian rights,”Hanan Ashrawi, a senior Palestinian politician, said ahead of the summit.

Some in Israel, however, are already cheering the end of an era. An article in the Jerusalem Post on Thursday said the message from Warsaw was clear. Palestinian leaders do not have a veto on which Arab countries can ally with Israel. “The long-held assumption that the Arab world would not deal with Israel until the Palestinian issue is solved has proven empty,” it said.