But United States President Barack Obama does say that. In fact, they gave him the Nobel Prize for saying it, didn't they?
Speaking in a radio interview, Mr Lieberman added: "There are conflicts that have not been completely solved and people have learned to live with it, like Cyprus ... . We have to be realistic. We will not be able to reach agreement on core and emotional subjects like Jerusalem and the right of return of Palestinian refugees."
And he said all this just as Mr Obama's point man for what we used to call the peace process, George Mitchell, arrived in Israel.
Undaunted by Mr Lieberman's comments, Mr Mitchell gabbled the usual nonsense about how "we're going to continue our efforts to achieve an early relaunch of negotiations ... because we believe that is an essential step toward achieving a comprehensive peace".
Doesn't he understand that the peace process has been dead for years? It is no more. It has expired. It is an ex-peace process.
Yes, of course he knows, but it was Mr Lieberman who went off-script, not Mr Mitchell. Every Israeli government since 2000 has believed what Mr Lieberman said and acted accordingly, but has colluded with the United States and various well-meaning Europeans in pretending otherwise.
The Palestinian Authority under Mahmoud Abbas also pretends that the peace process is still alive. Indeed, it did so even in the last years of Yasser Arafat's life. It has to go on pretending, because if the authority admits that the peace process is dead, then it becomes no more than an Israeli instrument for indirect control of the Palestinians. As it often is, in practice.
We had a vivid demonstration of this recently, when Judge Richard Goldstone submitted his report on last winter's three-week war in the Gaza Strip to the United Nations Human Rights Council.
The 575-page document reported that both Israeli forces and Palestinian militants had committed war crimes and possible crimes against humanity, and a resolution was put before the council that could ultimately have led to prosecutions at the International Criminal Court in The Hague.
Israel launched a propaganda blitz to discredit Judge Goldstone's report, and together with the US, it mounted a diplomatic campaign to postpone any formal consideration of the report until next March.
By then, it would be old news. Standard tactics, but here's the bizarre bit: the Palestinian Authority also supported delaying the vote by six months.
What possible reason could the authority have for doing such a thing? Well over a thousand Palestinians had been killed in the conflict, and only 13 Israelis.
The only Palestinians accused of war crimes were the militants of Hamas, who rule the Gaza Strip, and they are the sworn enemies of Abbas, his Fatah movement and the Palestinian Authority. It was a no-brainer, and yet the authority went along with the Americans and the Israelis.
Unsurprisingly, this public evidence of the authority's subjugation to American and Israeli policy caused a great outcry among Palestinians even in the West Bank, and Mahmoud Abbas ordered a "probe" into who had made such a wicked decision (hint: his initials are M. A.).
The truth is that the Palestinian Authority is just as complicit in the charade of a continuing peace process as the Israeli or US Governments, and cannot afford to abandon it.
Only the radical Islamists of Hamas, from their besieged enclave in the Gaza Strip, openly acknowledge the same reality that Avigdor Lieberman describes (although from a very different perspective).
There is no peace process, and the two-state solution on which it was built is all but dead. So what they offer Israel, at best, is a long-term truce - but only if the Palestinians get their pre-1967 borders back now.
A long-term truce ("like Cyprus") is all that Mr Lieberman is offering - and even that is not going to happen because he has no intention of returning to Israel's pre-1967 borders. Neither does his boss, Prime Minister Binyamin Netanyahu, although he wraps his refusal in more diplomatic language.
All of Mr Obama's pleas have failed to extract from Mr Netanyahu even a promise to freeze the expansion of Israeli settlements in the occupied territories, let alone to negotiate a withdrawal from them.
He has not moved from pleas to actual pressure because the Israelis effectively control the US Congress on this issue, and he will not risk alienating Congress over Israel while he is trying to get legislation through on health care, climate change and other urgent issues.
He cannot even order the Israelis not to attack Iran. They will do it if they want to, even if the bulk of the Iranian retaliation would fall on American bases and forces in the Gulf, Iraq and Afghanistan.
Still, there is no doubt that Mr Obama's intentions are good. So are mine. Where's my prize?
• Gwynne Dyer is an independent London journalist.
