Jerusalem — When winter rains turn the back roads of Lebanon to mud, it is easy to get stuck in the mire, local residents say. Many Israelis are beginning to feel the same thing is happening to their forces in Lebanon.
Israel and Lebanon so far have not been able in five meetings to agree on an agenda for negotiations on removal of Israeli and other foreign troops from Lebanon and on future relations between the two countries. President Reagan sent special negotiator Philip C. Habib back into the breach in hopes of spurring movement, and a compromise based on a US plan may be in the offing.
But in the meantime the number of daring attacks on Israeli soldiers in Lebanon is increasing weekly, as are the casualties.
Since Sept. 29, when Israeli troops pulled out of west Beirut, 17 Israelis have been killed and more than 90 wounded (apart from a building collapse in Tyre due to a gas leak that took 76 Israeli lives and injured 27). But nine of the deaths and almost half the injuries have occurred since Dec. 1, with 13 incidents during the first week of January.
The perpetrators are reportedly Palestinians infiltrating back into south Lebanon, Lebanese leftists, as well as, in one case, Lebanese Shiite Muslim adherents of Iranian leader Ayatollah Khomeini.
Talks with soldiers in Lebanon and reports in the Israeli press indicate that morale is low, especially in the Shouf mountain region where Israeli soldiers are exposed to cross fire from warring Lebanese Christians and Druze sect militias.
Hirsh Goodman, military correspondent of the Jerusalem Post wrote, ''The youngsters manning the roadblocks, sitting on tanks along the highway as bullets whiz over their heads, have opted for macabre humor rather than logic to explain their daily routine. The minute you ask a question you are asked another question: 'Well, when are we leaving?' '' Mr. Goodman added, ''They are sick of the scenery, the winter, the people, and the problems that remain unfathomable. They understand the need for security on Israel's northern border but they don't understand what they are doing in the Shouf, being fired on and not being able to fire back.''
Israeli television caused a scandal in late December when it ran a shot of Israeli soldiers singing a cynical parody of an Israeli nursery rhyme: ''Airplane come down to us, throw us off to Lebanon, we will fight for [Israeli Defense Minister Ariel] Sharon, and return in a coffin.''
The Israeli Army has increased its patrols south of Beirut and ordered troops to be on the alert for ambushes. Other Israeli soldiers have had to cope with keeping warm as they man mountain posts deep in six feet of snow. A newly formed Israeli Army alpine unit had to rescue a column of supply vehicles stuck in snow.
A small group of demonstrators from the ''Peace Now'' movement sang outside the prime minister's office on Sunday a new version of the now-famous ditty: ''Airplane come down to us, take us out of Lebanon, because we're sunk in the mire, and don't see how to get out.''
While Israeli antiwar activists traditionally do not refuse to fight, given the country's beleaguered history, a protest group called Yesh Gvul (There's A Limit) has gathered signatures of 1,500 soldiers, mostly reservists, asking that they not be called to serve in Lebanon.
So far, despite the mounting casualties, public support for the government appears to be holding steady, but observers here say continued casualites in Lebanon without political compensation could turn the conflict there into a political liability.
At this point, the government appears determined to hold fast to its demand for political normalization with Lebanon as the reward for its military efforts. ''The Israeli Army will stay in Lebanon until a political agreement is reached, '' Israeli Chief of Staff Rafael Eitan said on Tuesday.
Defense Minister Sharon conceded in a recent television interview that it was difficult for the soldiers on the front line, but he stressed that the Israeli Army must remain in the Shouf mountains to retain control over the strategic Beirut-Damascus highway.
Deputy Foreign Minister Yehuda Ben-Meir was reported here to have told US negotiator Morris Draper that if the US counted on the Israeli public's weariness with Lebanon, which he conceded, to force the government into a speedy withdrawal, it was mistaken. He said the government could convince the public that normalization was essential before withdrawal.
But rumblings of discontent with government policy are appearing within the Cabinet from ministers who dislike Mr. Sharon. Deputy Premier David Levy and Communications Minister Mordechai Zipori were promised a special Cabinet debate by the prime minister on whether Israel's Lebanon policy is still appropriate. Mr. Zipori said the debate was needed in light of continuing casualties.
Former Labor Party Prime Minister Yitzhak Rabin, who initially backed the conduct of the war, this week called on the government to admit that the goal of using Israel's armed might to impose a formal peace agreement on Lebanon is a ''mistake, an illusion'' and to concentrate now on securing Israel's minimum security needs in the north.