The fine details of US President Donald Trump’s Israeli-Palestinian peace plan will be revealed after the oncoming Israeli general elections. According to media reports, the American leader will allocate around 90% of the West Bank for the establishment of an independent Palestine. President Trump’s peace plan poses a major strategic and diplomatic threat to Israel.The Palestinian Authority President Mahmoud Abbas has already announced he will rebuff any American peace offer. This rebuff only aggravates Israel’s dilemma: If Israeli leaders reject the peace plan, they will be no different than Abbas in personally scorning President Trump. Since the current president has shown unprecedented support for the Jewish State, this gesture would be particularly humiliating for the current American administration.However, if Israel accepts President Trump’s peace plan while the Palestinian leadership rejects it, future peace proposals will very likely demand additional Israeli concessions to the Palestinians. In other words, as dismal as ceding 90% of Judea and Samaria may appear today, the current peace proposal could set the lowest possible bar for international community demands from the Jewish State in coming years.This bar is low because it is unlikely that the next American administration will be as pro-Israel as the administration of President Trump. If the Democratic Party were to take over the White House, Israel will hardly receive the support it has been accustomed to traditionally receive from America. It is not only the emergence of avowedly anti-Israel politicians like Ilhan Omar, Rashida Tlaib and Alexandria Ocasio-Cortez in Democratic Party rows that bodes ill for Israel. The leftward shift among Democratic Party grassroots activists has pushed even a party heavyweight like Elizabeth Warren to launch unprecedented attacks against Israel’s leadership and for several Democratic candidates to desert the latest AIPAC conference.Israeli leaders need to react wisely to the dark clouds amassing over Israel’s diplomatic horizon. Israel must focus on making the Palestinian leadership pay a steep price for rejecting President Trump’s peace proposal. Israel must punish Mahmoud Abbas precisely because at present he sees no major downside in scorning President Trump.Israel needs to make the Palestinian Authority understand that the Trump peace plan is the best peace agreement it will ever sign – not the worst possible agreement as is today the consensus in Ramallah. The Palestinian Authority will only understand this if Israel makes it clear that any off-hand Palestinian rejection of Trump’s peace plan will result in Israel immediately annexing the portion of the West Bank that Trump’s plan envisions should remain part of Israel.This is an effective measure to weaken – rather than strengthen – the negotiation position of the Palestinian leadership in future rounds of negotiation. Furthermore, this threat could receive the support of the current American administration for two reasons: Firstly, it is a powerful incentive for the Palestinian leadership to respond positively to President Trump’s peace plan. Secondly, it would painfully punish the Palestinian leadership for its intransigence and personal affront to the American president.It is possible that despite annexation threats, the Palestinian leadership will insist on rejecting this peace proposal, just as it has rejected all past peace proposals. It is likely that any Israeli annexation in the West Bank will be followed by vociferous Arab and European protests, UN resolutions condemning Israel and even by another intifada in Judea and Samaria.It might be tempting not to court this scenario by avoiding measures that are considered provocative by the international community. However, the deeper truth is that only the prospect of “provocative” measures by Israel will make the Palestinian leadership understand that time is not on its side and that all Palestinian dreams of pushing Israel back to 1949 ceasefire positions are chimeric.The prospect of Israel annexing portions of the West Bank which the peace plan offers to the Palestinians will encourage the Trump administration to strike a careful balance between the security concerns of Israel and Palestinian aspirations to receive a territorially contiguous state in the West Bank. If the Trump administration were excessively impartial to Israel in its map-drawing, Israel might otherwise be tempted to annex territories in the West Bank that the United States is not willing to cede to Israel. On the other hand, if the US offered areas to the Palestinian Authority which infringe Israel’s security, the Trump administration would alienate its electoral base of Evangelical Zionist supporters.Israeli political leaders across the Zionist spectrum should support Israeli annexations in the West Bank were Abbas to reject President Trump’s peace offer. Israel needs to make a clear statement with American support that the Jordan River valley and the main settlement blocks in Judea and Samaria will not be cleansed of their Jewish residents as part of any future peace agreement. If the Palestinian leadership remains unscathed after rejecting the peace proposal, future peace plans tabled by American leaders and by the international community are likely to jeopardize Israel’s security.Israel must transform the threat posed by this American peace plan into a strategic opportunity. Israel needs to leverage its strength and diplomatic credit in Washington to dispel any Palestinian ambitions of additional Israeli concessions in a post-Trump world. Dispelling these ambitions is crucial to asserting Israel’s vital interests and making peace possible between Israelis and Palestinians.Rafael Castro is a Yale- and Hebrew University-educated political analyst based in Berlin. His pieces on Middle Eastern politics appear regularly in Israeli media.