Jerusalem — You might call it a belated valentine.
President Reagan's message of reassurance to Prime Minister Menachem Begin is designed to cool the latest flurry of tensions between this country and its superpower supporter - this time over possible arms sales to Jordan.
But the anxious exchanges of the past few days are just one more surface indicator of the underlying but growing strains between Israel and the United States.
Defense Secretary Caspar Weinberger's remarks about possible sales of sophisticated American weaponry to King Hussein brought almost all shades of Israeli opinion together in a sharply negative response. Mr. Begin said that such a sale would violate American commitments to Israel. Parliament voted 88-3 to urge the US to ''refrain from a danger so grave to Israel's security.''
In reply, President Reagan's Feb. 16 message emphasized that there were no plans to sell missiles or advanced jets to King Hussein. The US was determined to maintain Israel's military superiority, he said soothingly.
But this fresh exchange has come in the wake of a series of acrimonious differences - going back to the angry American reaction to Israel's bombings of Iraq's nuclear reactor and of Beirut last summer (US jet deliveries were temporarily suspended) and to last December's near-annexation of the Golan Heights (the new US-Israel security agreement was suspended and the US joined the United Nations Security Council condemnation of Israel).
Relations between the two governments reached their lowest level during the prolonged debate in Washington over the sale of advanced American weapons, including AWACS surveillance planes, to Saudi Arabia last fall.
This time, Israeli Prime Minister Menachem Begin is described here as intent on nipping any new AWACS-type deal in the bud -- with bipartisan backing. He is determined, foreign analysts here say, to make sure that the US does not seriously realign its Middle East policy nor try to distance itself from Israel. Hence Mr. Begin's quick and angry rejection of any such US-Jordan arms deal.
The Reagan administration, on the other hand, is trying to broaden and deepen its contacts with the more moderate Arab states in hope of making further progress toward a wider peace. But with ''stage one'' of Camp David (the Egypt-Israel peace treaty and the Sinai withdrawal) due to be completed by April 25, and ''stage two'' (the Israeli-Egyptian talks on Palestinian autonomy) stalled, there is little sign of any alternative peace process. In the interim, the American Defense Secretary has reached out to the Arabs to help shore up the US military strategy for the region.
Speaking on the NBC ''Today'' show this week, Mr. Weinberger said that he had suggested during his just-completed trip to Saudi Arabia, Oman, and Jordan not that the US was moving away from Israel but rather that Washington needed ''more than one friend in the Middle East.''
A senior US official on the Weinberger plane appeared to take a more severe stand. The official was reported as saying that American responses to Israel's bombing raids and Golan Heights move ''indicate a change of policy . . . that should be clear.'' Such ''unilateral acts by anyone are not acceptable.''
On Feb. 16, however, Mr. Weinberger joined the Reagan-led effort to calm the squall. He stressed that there was no Jordanian request for missiles and advanced jets pending and that if such a request was received it would be considered with the US commitment to Israel in mind. ''So talk of an arms sale to Jordan, because we had discussions in Jordan about it, really is quite premature,'' he said.
Middle East neighbors Israel and Jordan have had a special relationship since the end of hostilities in 1967: simply put, Israel is in the driver's seat and intends to stay there. This is the gist of Israel's specific argument with the Reagan administration against the US selling sophisticated Hawk ground-to-air missiles and F-16 fighter planes to Jordan.
Israeli officials indicate they do not accept the American contention that by selling arms to Jordan the US prevents King Hussein from buying from the Soviets and thereby ensures the moderation of the kingdom. Instead, they fear that a suddenly radical, well-armed Jordan might turn to Moscow for aid against possible Israeli ''preemptive action.''
The relationship between Jordan and Israel is at best a delicate one. There is no Camp David-like peace treaty between the two countries. King Hussein steadfastly refuses to break away from the Arab world in the same way as Egypt's Anwar Sadat in order to come to terms with Israel. But in almost every other way Jordan is Israel's most normal neighbor.
Each morning West Bank produce trucks and East Bank workers traverse the narrow Allenby Bridge between Jordan and the Israeli-held West Bank. Guerrilla infiltrators are usually nabbed by Jordan before they can cross the river into Israeli territory.
Diplomatic sources say King Hussein and his emissaries have met numerous times with Israeli leaders and at least once, in 1970, Israel stood ready to intervene in Jordan to protect King Hussein.
But since Jordan's defeat and withdrawal from the West Bank and east Jerusalem in 1967, the most important pillar in the Israeli-Jordanian relationship has been Israel's military superiority over Jordan. And Israeli military officials do not want that fact to change.