Israel's widening objectives shake Mideast balance; In its words and actions Israel moves beyond its original, limited war aims

Israel's limited war aims in Lebanon appear to be giving way to more ambitious objectives.

That, at least, is the implication of the latest battlefield developments and the tenor of Israeli announcements.

By late June 9, Israeli troops had penetrated 50 miles into Lebanon - twice as deep as the target set by Prime Minister Menachem Begin early this week. He said then the Army had been ordered only to push the Palestinians out of artillery range of Israeli settlements.

Israeli forces have been challenging Syrian control of the Beirut region with increasing boldness. They have been threat%wzo o cut off large pockets of Syrian troops in and near the Lebanese capital by interdicting the Beirut-Damascus highway.

At the same time, a new note was injected into the carefully modulated Israeli position June 8 when ''reliable sources'' told military correspondents that the Israeli Army had reinforced its troops on the Golan Heights following skirmishes with the Syrians in Lebanon. It was a warnqng to Damascus that Israel could open another front against Syria if provoked, one not distant from the Syrian capital.

Israel is operating confidently from a position of strength augmented by mobilized reserves. The elimination of the main centers of Palestine resistance leaves the bulk of the Israeli force free to deal with the Syrian Army.

Israel has called upon Syria to avoid confrontation and has consistently played down Syria's military reaction as ''token'' or as ''limited'' moves.

But by mid-week Syrian involvement in the fighting had increased markedly. Syrian fighters, according to the Israeli spokesman, attacked Israeli ground forces near Beirut June 8. The following day, Wednesday, Syrian MIGs took off in a mass response to heavy Israeli air attacks on Syrian missile emplacements in Lebanon's Bekaa Valley. In the dogfights that followed, Israel claimed to have shot down 20 Syrian jets without Israeli loss. Syria claimed 10 Israeli losses to five of its own.

Meanwhile, the Israelis have responded forcibly to Syrian moves which include air, artillery, and tank skirmishes.

Israeli sources have indicated that Israel's political objectives in Lebanon include the permanent clearance of a 25-mile buffer zone from the Palestine Liberation Organization (PLO) ''and those who support them.'' Long-range Israeli objectives include having the Lebanese government extend its authority over south Lebanon, sources said.

US special envoy in the Middle East, Philip C. Habib, is said to have borne this message from Jerusalem when he flew to Damascus June 8 to meet President Hafez Assad. Israeli government sources denied reports that Israel would demand a pullout of Syrian troops froi Lebanon as a condition for the pullout of Israeli troops.

Israel's reported position within one mile of the Beirut-Damascus highway and the virtual encirclement of Syrian units in the area backs Israel's diplomatic position with significant military pressure.

The extent and forcefulness of the Israeli thrust into Lebanon have surprised even Israeli observers. The Israeli daily newspaper Haaretz warned June 8 against drawing the Syrians into a confrontation.

''One gets the impression,'' said an editorial, ''that certain ministers have become intoxicated by the victory achieved thus far.'' It said that Defense Minister Ariel Sharon was pushing for a policy aimed at removing the Syrians from south Lebanon or all of Lebanon. Thus far, the Israeli government has given no sign of making such a demand.

If the Syrians choose a head-on confrontation with the Israelis, Israeli officials apparently believe Israel has amassed enough military power to dictate terms when the battle is over.