WASHINGTON (Reuters) - As he stood on the podium next to Israeli Prime Minister Benjamin Netanyahu, U.S. President Donald Trump said he was open to new ideas that would bring Middle East peace. With that, he opened the door to a whole new maze of complexity and risk.

U.S. President Donald Trump (R) reaches to greet Israeli Prime Minister Benjamin Netanyahu after a joint news conference at the White House in Washington, U.S., February 15, 2017. REUTERS/Kevin Lamarque

By uttering the phrase “one-state” - rather than a two-state solution to the conflict, the bedrock of international diplomacy for two decades - he went where past presidents and most leaders feared to tread, knowing the loaded implications.

The creation of a binational or single state that encompasses both Israel and Palestinian territories is not a viable option for most Israelis and Palestinians for religious, political and demographic reasons.

“So I’m looking at two-state and one-state, and I like the one that both parties like,” Trump said with an almost offhand air, emphasizing that for him the main aim was “to see a deal.”

“I’m very happy with the one that both parties like. I can live with either one.”

The problem is the parties - Israelis and Palestinians - may find it just as hard, if not harder, to live with a one-state solution as two states side-by-side, depending on how it is defined and what ideals underpin it.

While not the taboo it was a few years ago - Israel’s president is an advocate and many younger Palestinians discuss the concept - the idea of one state is freighted with questions of identity, ethnicity, religion and democracy that cut to the essence of the conflict.

Saeb Erekat, the Palestinian chief negotiator, suggested the overriding risk was that Israel ended up holding the upper hand, creating one state with two separate systems - one for Jews and one for Arabs - mirroring South Africa’s apartheid.

ONE SECULAR STATE?

With efforts to forge a two-state solution having largely gone nowhere in the last 20 years, despite exhaustive international effort, it is natural that leaders and diplomats begin to examine other possibilities. In that respect, one state can seem a simpler, cleaner and more elegant solution.

But at the heart of Israel’s identity, from before its creation nearly 70 years ago, is the idea that it is a nation for the Jewish people. One of Netanyahu’s core and unwavering demands is that Palestinians recognize Israel as a Jewish state.

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If one state is created from the estimated 16 million people now living in Israel, Gaza, the West Bank and East Jerusalem, it would be extremely difficult for it to remain both Jewish and democratic - nearly half the population is Muslim or Christian, and the Palestinian birthrate is rising more rapidly than the Israeli one.

Academics and free-thinkers on the left and the right often circulate proposals for a single, binational state, or some similar formulation, but in opponents’ minds that quickly raises questions about the primacy of law and language, and whether the Palestinians, who have so long lived without a state, would have equal billing within a binational structure.

Beyond the many profound issues of identity lie simple-sounding but thorny questions: What would the single state be called? Could it be secular and Jewish? Would Muslims from other states be free to visit? Which legal system would apply? Would Arab or Muslim countries recognize the new entity?

DIFFERENT MEANINGS

To many settlers on Israel’s right, the term “one state” can mean Israeli sovereignty over the entire West Bank, while to some on the left in Europe and the United States, it can be a euphemism for a binational state with no Israel, said David Makovsky, director of the Project on the Middle East Peace Process at the Washington Institute.

“Whoever uses this term needs to be very careful in how it is used since it means opposite approaches,” he said. “Polls show only a minority of Israelis and Palestinians favor either definition of one state.”

A poll on Thursday showed exactly that. The survey of 2,400 Israelis and Palestinians conducted by the Tami Steinmetz Center at Tel Aviv University and the Palestinian Center for Policy and Survey Research in Ramallah showed 55 percent of Israelis and 44 percent of Palestinians favor a two-state solution.

The survey showed far lower support for a one-state outcome.

That is perhaps one reason why Netanyahu was careful not to reference a one-state solution at the news conference. He knows that buried behind the one-state label are concepts that could undermine the essence of an independent Jewish state, while not being attractive to the Palestinians either.

Briefing reporters after meeting Trump, Netanyahu did not rule out two states, saying his language on it had been consistent since 2009, when he made a landmark speech accepting the objective, albeit with conditions.

On Thursday, Trump’s ambassador to the United Nations, Nikki Haley, told reporters: “We absolutely support the two-state solution but we are thinking out of the box as well.”

Trump may not have known quite how loaded his mention of a one-state solution was, but he also emphasized it was not up to him in the end. The parties must agree.

“I’m happy with the one they like the best,” he said.