Israel's anxieties about its relations with the United States have been heightened by two recent developments:
* The Saudi agreement with US Defense Secretary Caspar Weinberger Feb. 9 to establish a joint US-Saudi defense committee.
* And unusually outspoken criticism by US Senate Foreign Relations Committee chairman Charles Percy (R) of Illinois of several recent Israeli actions--especially its virtual annexation of the Syrian Golan Heights. Senator Percy said, ''Israel cannot expect the United States to continue isolating itself from the world community to defend questionable actions and policies.''
Both developments are unsettling because they could suggest two things to Israelis:
1. That the US is simply not going to be deterred from giving Saudi Arabia a key role in overall Western defense planning for the Gulf, even if it is at Israel's expense.
2. That the groundwork is continuing to be laid in Washington for pressure to be more forthcoming on the deadlocked Palestinian issue once Israeli withdrawal from occupied Sinai is completed April 25. If Israel feels this is, indeed, happening, it is likely to find little comfort in the Reagan administration's latest efforts to accommodate Israeli sensitivities. These included last week's vigorous defense of Israel in the United Nations General Assembly and Mr. Reagan's refusal to make concessions on the Palestinian issue sought by Egyptian President Hosni Mubarak during his Washington visit.
Probably the biggest single threat to Israeli interests in the Middle East right now is the developing US-Saudi relationship. Israel's attitude to the Saudis was apparent in the fierce rearguard action to try to block last year's sale of sophisticated AWACS planes to Saudi Arabia. And Saudi Arabia continues to be the target of ridicule or attack in pro-Israeli American publications.
But for the defense establishment in the US, in particular, Saudi Arabia has a key role to play in Gulf security planning. Defense of Gulf oil against any Soviet threat has high priority in Washington, and Saudi cooperation is needed in contingency planning for the US Rapid Deployment Force being established to that end. The 1983 budget figures just released include some $4.4 billion for the force.
What worries the Israelis is the possible price the Saudis will extract from the US for their cooperation in developing minimal logistic support for the force--presumably a prime topic for the new US-Saudi defense committee.
Somewhere down the line the Saudis are likely to demand a more active and sympathetic US role on any Saudi initiative for overall peace in the Middle East. Saudi Crown Prince Fahd's peace plan, which was pushed last August but is now on a back burner, included a call for an independent Palestinian state with east Jerusalem as its capital.
Such suggestions are anathema to Israelis, who see them as the thin end of the wedge for the eventual dismemberment of their state. The Saudis imply that this is not so. Their line is that the Arabs would accept an Israeli state in return for Israeli acceptance of a Palestinian state. In any case, Israeli fears center on the prospect of the US eventually being persuaded to pick up a Saudi peace plan and run with it.
For Israel, its last line of defense or support in the US has usually proven to be in the arena of American domestic politics. In the past pro-Israeli pressures have often proven effective in the US Congress.
But for Senator Percy, on his return from an extended Middle East tour, to call some Israeli initiatives ''questionable'' and ''objectionable'' must set Israeli alarm bells ringing - even if Mr. Percy has a record of being more measured than some other senators in coming to Israel's defense.
If this has stirred Israel's fears to consider making points with military action against the Palestinians or the Syrians in southern Lebanon, the US is already moving to head this off by letting it be known it is sending special envoy Philip C. Habib back to the region.
At the same time, it must be recalled that events in the Arab world rarely unfold in a predictable way.
For example, there are some potential catches in the US-Saudi agreement for a military committee. The two partners do not see eye to eye on who is the biggest threat to them. For the US, it is the Soviet Union; for the Saudis (and the rest of Arab public opinion), it is Israel - and after that, Iran.
Furthermore, because of Arab sensitivities, the Saudis are likely to be coy and equivocate in public about the meaning of the military committee. And then there is the question of what that chronic but important Arab maverick, Syria, may do at any time to upset the applecart.