US experts concerned with the Middle East are focusing on two pockets of turbulence, both bearing directly on American interests in the region. One is political turmoil in Israel, with its implications for Jerusalem's future policy in Lebanon and on the occupied West Bank and Gaza.
The second is the latest phase of the vicious war between Iran and Iraq, casting a possible shadow over the stability of Saudi Arabia and the sheikhdoms of the oil-rich Persian Gulf.
Of the two situations, some US analysts consider the Iran-Iraq war to be the less predictable and more dangerous.
One indication of Persian Gulf tension is the intense rivalry between Iran and Saudi Arabia for effective control of the 13-member Organization of Petroleum Exporting Countries.
Behind this rivalry, a high-ranking US official said, lies deep hostility between Iran's revolutionary brand of Islam, typified by Ayatollah Ruhollah Khomeini, and the conservative Islamic regimes of Saudi Arabia and the sheikhdoms.
''One of the prime reasons we sell weapons to Saudi Arabia,'' the official said, ''is to help the Saudis prepare for any threat from Iran.''
Other sources say that a stockpile of modern weaponry in Saudi Arabia could be important for the United States itself, if American forces had to be brought in swiftly to defend US interests in the Gulf.
Recently, for example, according to William B. Quandt, a former staffer on the National Security Council and now of the Brookings Institution, American-operated AWACS planes based in Saudi Arabia detected an Iranian warplane approaching Saudi oil fields. Saudi interceptor aircraft were scrambled , and the intruder turned back.
Iranian penetration of southern Iraq - the apparent goal of Tehran's current military offensive - could open the way for Iran to exert pressure directly on Kuwait, the tiny oil-rich sheikhdom that lies between Iraq and Saudi Arabia.
In developments over the weekend, Iraq was reported to have attacked Iran's main oil terminal at Kharg Island by air and sea. An oil tanker at anchor there was among the Iraqi targets.
All through the string of Gulf sheikhdoms - and in the eastern regions of Saudi Arabia - live hundreds of thousands of Shiite Arabs, adherents of the Islamic sect dominated by Ayatollah Khomeini.
These Arabs, plus many Iranian Shiites living and working in the sheikhdoms, provide fertile ground for Tehran's drumfire of propaganda against the Sunni Muslim conservatives of the Saudi, Kuwaiti, and other ruling families of the Gulf.
At this point no one can be certain how the Israeli political situation will sort itself out, except that overall control is likely to remain with Prime Minister Menachem Begin and his coalition government.
Indeed, if Ariel Sharon remains in the Cabinet and if Moshe Arens, currently Israeli ambassador to the US, becomes defense minister, the Begin administration's hawkish outlook could be strengthened.
Mr. Arens had doubts about the Camp David agreement, opposed the demolition of Jewish settlements in Sinai, and supports a vigorous Israeli settlement policy on the West Bank.
No matter what shape the Israeli Cabinet finally takes, former Undersecretary of State Joseph J. Sisco says, the ''underlying fundamental issues'' that engage Washington and Jerusalem will remain.
''Troop withdrawal from Lebanon,'' Mr. Sisco says, ''and the future of the West Bank will apply to any Israeli government.''
US experts generally agree that Israel's boiling political tensions may force a slowdown in the talks among Lebanese, Israeli, and US officials on withdrawal of foreign forces from Lebanon.
But in the long run, in Mr. Sisco's view, ''neither Israel nor Syria has a real interest in staying indefinitely in Lebanon.''
Israeli forces now occupy south-central Lebanon. An estimated 30,000 Syrian troops dominate the northern part of the country and Lebanon's fertile Bekaa Valley. The authority of President Gemayel's Lebanese government is limited largely to Beirut and an enclave north of the capital city.
Sisco foresees an eventual foreign troop withdrawal from Lebanon, but ''only after much patient effort.''
Meanwhile, in his view, ''it would be timely for King Hussein of Jordan to come forward, to strengthen those Israeli elements who favor (a continuing) peace process'' between Israel and its Arab neighbors.
''Hussein,'' Mr. Sisco says, ''has a unique opportunity to tip the balance toward compromise,'' leading to some form of joint Jordanian-Palestinian administration of the West bank and Gaza.
For some time, Hussein and Yasser Arafat, leader of the Palestine Liberation Organization (PLO), have discussed what kind of Jordanian-Palestinian entity might negotiate with Israel on the future of the disputed territories.
King Hussein, according to informed sources, is hesitating, partly out of fear that Arafat and the PLO leadership might later abandon him, jeopardizing Jordan's position among other Arab states.
Saudi Arabia, for example, might be persuaded to give tacit backing to Jordanian-Israeli talks on the West bank - but only if Arafat and the PLO agree.
To prod the Jordanian monarch to negotiations, the Reagan administration is understood to have given Hussein - verbally and in writing - assurances of strong US support. These include a large package of future military aid to Jordan and a promise to put pressure on Israel to freeze Jewish settlements on the West Bank.
Some observers doubt the wisdom of such assurance, since the Begin government refuses to accept a settlements freeze and because the US Congress might not approve extensive military help for Jordan.