Beirut — Israel is not the only one ready to fight.
Palestine Liberation Organization chairman Yasser Arafat is under ''immense pressure'' to pull the trigger and break the July 24 cease-fire in southern Lebanon to which the PLO is committed.
Well before diplomats here in Beirut and US intelligence reports warned of an Israeli buildup on the border, factions under the PLO umbrella were lobbying for an end to the truce.
But until the PLO central committee gets a majority vote favoring a break of the cease-fire, those factions have their hands tied militarily, a Palestinian source said.
''The choice between diplomacy and armed struggle has always been controversial in the revolution. . . . There is immense pressure on Arafat after the West Bank uprising. How long he can hold out is another question,'' he said.
Although the PLO is made up of eight groups, only three have the numbers and firepower to count. And among those three, there is no doubt that Fatah is the heavyweight of the group.
A moderate guess is that Fatah numbers about 14,000 guerrillas. The next largest group is the Popular Front for the Liberation of Palestine (PFLP) with about 6,000 men, sources said.
Although the Democratic Front for the Liberation of Palestine (DFLP) runs a close third with almost equal manpower, the PFLP has superior weaponry and greater popular support, one Palestinian source said.
The rest of the groups have anywhere from 500 to 2,000 fighters (giving the PLO a total force of about 25,000), but they have negligible political influence within the PLO.
Both the PFLP and the DFLP want an end to the cease-fire, but both stop short of doing it alone -- although each claims it is able.
''We are now having many contacts with PLO factions and Lebanese factions to break the cease-fire,'' said PFLP spokesman Omar Kataish.
''By this cease-fire, we abandoned one of the most sacred rights of the Palestinians -- the right to fight. This will cast doubts on the Palestinian revolution.
''The dangers of the cease-fire in the south are much bigger than the dangers of the fight in the south,'' Kataish said.
He said the truce poses major dangers.
What sense, he asked, does it make for the PLO to ask Arab League countries (and Jordan) to open their borders for PLO infiltration into Israel when the PLO has voluntarily closed the main stronghold in south Lebanon to such raids?
He also believes the Lebanese will wonder why there is such a large-scale Palestinian military mobilization in their country if it is not to battle Israel.
Moreover, the PFLP thinks adherence to the cease-fire will decrease PLO popularity among Palestinians in the occupied West Bank and Gaza Strip.
''Palestinian children were fighting with stones. . . . Palestinian citizens were using knives against well-armed Israeli soldiers while the best armed Palestinian fighters in south Lebanon were silent - like other Arab soldiers.''
''This has been a shock for the Palestinian people.''
PFLP spokesman Jamil Hilal echoed his comrade's sentiments.
''It is very difficult right now to keep them (PLO guerrillas) quiet and calm.''
''The cease-fire for the DFLP applies only conditionally to the south. . . . In cases where (Israeli Prime Minister Menachem) Begin and the military have exceeded the limit in using the Army and police against Palestinians in the occupied territories, then the cease-fire is a sham.''
Yet PLO sources said Arafat believes there is diplomatic mileage to be gained from maintaining the cease-fire.
And most important, some Palestinian sources said the PLO is short of weapons despite Israeli claims of reinforcement since the truce.
''Arafat can afford to be a victim only. He can't afford to launch military action,'' one source said.
''We are not against diplomatic means, but diplomatic means is only complementary to other means of struggle,'' Hilal said.
''If Arafat gives more weight to diplomatic means, then this is wrong,'' the DFLP representative added.
Will the DFLP shatter the cease-fire by firing a few rockets at the northern Israeli settlements then?
No. The cease-fire ''has to be a political decision by the PLO,'' Hilal said. The PFLP also admitted it will abide by the PLO line despite its strong objections.
''We complied (with the cease-fire) because we don't want to exchange the steadfastness of July for an internal fight with Fatah,'' Kataish said.
Although Palestinian sources said there is a greater measure of democracy within the PLO these days, there is no way to avoid the fact that Fatah dominates.
''Yasser Arafat [through Fatah] can still put the screws on them,'' one source said bluntly.
The other groups are also dependent on Fatah for weapons and money, the source said. But both the PFLP and DFLP denied this.
''Collectively these groups can exert a lot of pressure on Arafat,'' the source said. And this is what is happening.
After the truce in July, the Popular Front for the Liberation of Palestine-General Command let loose a few shells to prove its distaste for the cease-fire.
Fatah sent its men in ''to straighten things out.'' Fatah suffered casualties , but the PFLP-GC left the truce alone after that.
''Arafat cannot put an end to all military actions. Then there would be no justification for the revolution, so the occasional strikes by the radicals keep the pot boiling and the boys happy,'' one Palestinian said.