WASHINGTON -- Britain questioned the productivity of an effort in Paris on Sunday to cajole Israelis and Palestinians back to the negotiating table, warning that international pressure risked "hardening positions" on both sides.Dozens of countries sent their senior-most diplomats to the conference, but the United Kingdom did not, ostensibly as a trust-building gesture to the incoming Trump administration.Prime Minister Theresa May sent neither her foreign minister, Boris Johnson, nor her envoy to France to the parlay. Britain instead had observer status at the conference."We have particular reservations about an international conference intended to advance peace between the parties that does not involve them– indeed, which is taking place against the wishes of the Israelis– and which is taking place just days before the transition to a new American President when the US will be the ultimate guarantor of any agreement," a Foreign Office statement read.The event was meant to underscore international support for a two-state solution to the Israeli-Palestinian conflict. US Secretary of State John Kerry traveled to Paris for the event in one of his final acts in office.But while most countries in attendance signed on to a communique urging the two parties to recommit to a two-state solution, and to cease "unilateral steps" that entrench the conflict, London demurred, ultimately choosing not to back the document.There are risks," the UK government warned, "that this conference hardens positions at a time when we need to be encouraging the conditions for peace." Trump officials expressed displeasure with the French government for hosting the conference, as they had with its predecessor event held in June of last year– a "waste of time," one Trump aide said to describe the effort to The Jerusalem Post over the summer. But according to State Department officials, Kerry's attendance at the conference was an expression of his support for a two-state solution– a rapidly dwindling prospect with the growth of Israel's settlement enterprise in the West Bank, the outgoing secretary argued last month in a policy speech. Israel's government repudiated his argument then, and the conference now, as contrary to the pursuit of peace.London last month scolded Kerry for the tone of his December speech, in which he described the Israeli government as the most right-wing in Israeli history. The focus of his speech was Israel's settlement activity.British officials did not immediately respond to a request for comment.Reuters contributed to this report.