Not many of us in Israel imagined, in recent years, that the fate of the Israeli-Palestinian conflict would be determined by outsiders. We always believed that our future should be discussed and negotiated between Israelis and Palestinians. Furthermore, the common view was that only the two sides should decide their fate and that we would not let anyone else impose a solution.

What is happening this week – the US moving its embassy from Tel Aviv to Jerusalem in recognition of Israel’s claim to Jerusalem as its capital – proves that we were wrong (or maybe bluffing). With this dramatic move, which runs counter to all previous international resolutions on Jerusalem, Donald Trump is determining the fate of the conflict on his own.

It turns out that when President Trump one-sidedly intervenes on behalf of the Israeli government, the previously declared Israeli approach is quietly sidelined; most Israelis (me excluded) welcome this decisive US intervention. Palestinians, on the other hand, are devastated and feel cheated. They have no ability to block the move but have already declared that this US administration has disqualified itself from serving as an honest broker.

The US administration is doing what the sides always objected to – it is one-sidedly determining the outcome of the conflict, destroying the hopes of creating two separate states and in the process reshaping the fate of the Middle East as a whole.

Since outside intervention in shaping our fate is already happening, why only the US? Why only Donald Trump? Where is the additional balancing move, Chinese, Russian, British or French? If the US can intervene on one side, why not each of the other four permanent UN Security Council members? Each following its principles and its best judgment. Or why not all four together?

Britain should be the first in line. It is true that the British mandate in Palestine ended 70 years ago this week, but Britain still knows better than any other country what is at stake: the peaceful coexistence of Jews, Muslims and Christians in the Holy Land and the upholding of international law. Britain has long espoused both of these principles.

Whatever may have been the British intention in 1917 with the Balfour declaration, or in 1948 when Britain left Palestine, is it the wish now that the “national home” for the Jewish people will become a Middle Eastern fortress while the indigenous Palestinians turn into its unwilling subjects? This outcome should not be accepted.

The British government in which Balfour was foreign secretary clearly favoured a Jewish “national home” but also added: “Nothing shall be done which may prejudice the civil and religious rights” of non-Jews in Palestine. Do the British people now feel comfortable with a one-state outcome as their record and legacy in Palestine?

People of goodwill on both sides of this conflict need Britain to speak up. Trump can act as president on behalf of the US, but not on behalf of the whole world. The UK parliament has already called upon its government to recognise the state of Palestine alongside the state of Israel – the aim being two states whose peoples enjoy equal rights. It happened in the Commons in October 2014 when MPs voted by an overwhelming majority to recognise Palestine (274 for; 14 against). Now is the time for implementation of that wish. This is the policy move that could counterbalance Trump’s one-sided and dangerous move of his embassy. Such a British act of recognition would reaffirm Palestinian basic rights, restore hope, and it would help create the much-needed parity of esteem without which no peace agreement can be just or sustainable.

I would even go so far as to say that if Britain (ideally co-ordinating its policy with France) recognised Palestine, it could save the equitable two-state solution and the possibility of a peace agreement between Israel and the Palestinians.

As an Israeli patriot who loves his country, I also see such a British move as vital to the preservation of Israeli democracy. Only the two-state solution that Trump has just fractured badly can guarantee a democratic Israel. A single bi-national state with a similar number of Jews and Arabs will not remain democratic. A British recognition would be historic and could bring about lasting benefits for both Israelis and Palestinians.

I know that such a move demands political courage, but we are speaking about principles that Britain claims to uphold and was always ready to fight for: freedom, justice and democracy.

• Dr Alon Liel is the former director general of the Foreign Ministry of Israel and was also Israel’s ambassador to South Africa. He is one of the instigators of an Israeli campaign to advance recognition of a Palestinian state by European parliaments and governments