He reminded Hussein of how, as a young king on a vulnerable throne, he had come to Washington in 1960 to discuss the dangers of communism with Dwight Eisenhower. The King, Mr Clinton said, had told Eisenhower: 'We need more than anything else to know that we do not stand alone.'
Now once more, he said, America could assure the King that he did not stand alone in the face of 'those who preach hate and terror'. Jordan and America were fighting 'the same battle - the struggle for peace. And I say, on behalf of the United States, we will not let you down.'
There was a clatter of applause from the assembly; the King's recent electoral laws had, in effect, prevented many Islamists from gaining seats, and those who did boycotted Mr Clinton's speech.
But the message was clear to every Jordanian opponent of the peace treaty - indeed, to every Muslim in the Middle East who suspects that the US is trying to replace the dead monster of communism with an even more frightening enemy: Islamic 'fundamentalism'.
There were assurances, of course, that America had no antagonism towards the religion of Islam. 'We respect Islam,' Mr Clinton said. Tens of thousands of American Muslims had heeded the Friday call to prayer. 'America refuses to accept that our civilisations must collide.' But again and again throughout his tour of Egypt, Jordan, Syria and Israel, the President made it clear that it was the 'terror' of Muslim fundamentalism with which America was at war.
The use of that one corrosive word 'terror' - employed by the Israelis for anyone who opposes them through force of arms, and now adopted by Martin Indyck, Mr Clinton's Middle East National Security adviser and former lobbyist for Israel in Washington - crept through every speech the President made. He lectured King Hussein on 'the face of terror and extremism'; he talked in Damascus of 'terrorist infiltration' and of 'murderous acts of terror'; he spoke in the Knesset of 'the merchants of terror', linking them in his Israeli speech with what he called 'the plague of anti-Semitism'.
Now America is ready to stand by a new circle of supposed allies: Israel, of course, Jordan, the PLO (in theory, at least) and potentially Syria - and to go to war alongside them against the new enemy of 'terrorism'. But what Mr Clinton did not say - could not say - is just what these 'terrorists' represent.
In his hours of speeches, those who made peace were praised as men of courage and wisdom and forethought - men who had made or were about to make what Messrs Clinton, Rabin, Arafat, Assad and King Hussein all refer to as 'the peace of the brave'. It is a curious expression for all of them to adopt, for it is another quotation from the 1960s: a remark De Gaulle made, not when the French leader was seeking alliances, but when he was abandoning France's Arab colony of Algeria.
No abandonment is intended now. This new 'circle' around Israel - Mr Clinton used the word in the Knesset - will be defended by America. But still, their 'terrorist' enemies remain only vaguely identified. Repeatedly, President Clinton suggested that wealth and prosperity could smother this terrible phenomenon - the old US policy of countering communism with dollars - but at no point did he attempt to address the reason why 'terrorism' existed.
To do so would be to acknowledge all that is unjust about the American-Israeli 'peace process' that is being installed at such extraordinary speed across the Middle East. To discuss Palestinian 'terrorism', for example, would require an explanation why Israel has never abided by UN Security Council Resolutions 242, 338 and 425, which demand the withdrawal of Israeli forces from occupied Arab land; and why America treats Israel's refusal to carry out these international obligations more leniently than it does, say, Iraq.
Such an explanation would also necessitate excuses for Israel's continued rule over the West Bank, of Mr Arafat's humiliation, of Israel's continued construction of Jewish homes on 'appropriated' (ie stolen) Arab land in east Jerusalem. And such explanations would force Mr Clinton to explain why Israel originally encouraged the Hamas movement, which both he and the Israelis now condemn as terrorists.
It would need a history lesson on the Palestinian refugees of Sabra and Chatila, slaughtered by Israel's Lebanese Phalangist allies in 1982. It would necessitate, in short, a resume of much of the injustices against Arabs - more importantly now, against Muslims - over the past decades.
But, meanwhile, woe betide any Arab leader who fails the test. There was, indeed, something of a McCarthyite flavour to Mr Clinton's Damascus press conference. Instead of 'Are you now or have you ever been a member of the Communist Party?', President Assad was repeatedly asked if he had been or was sponsoring 'terrorism'.
And by the end of the week, Mr Assad - who is insisting that Israel give back all Syria's territory in return for a full peace - was being categorised as 'the obstacle to peace' on radio and television (CNN repeatedly used this phrase on Thursday). Israel, which does not want to give back all Syria's land, apparently represents no obstacle at all.
It is a lesson the Arabs are beginning to learn. They must fall into line.
Those who do will be praised as men of vision; those who do not, as supporters of 'terrorism' - fundamentalist or otherwise - who will be America's new enemy.