Lebanon's government of warlords may no longer have sufficient grasp on the nation's rival forces to guarantee completion of a new security plan designed to end nine years of civil war.
The success of the scheme to disarm the militias and restore the divided capital to government control depends increasingly on the cooperation of extremist groups, both Muslim and Christian, that have emerged as major forces in recent months. And that cooperation is now seriously doubtful.
Many of the groups are comparatively new but have drawn enough supporters to threaten the traditional leaders who make up the ''national reconciliation government'' - and what could be Lebanon's last opportunity to pull itself together.
On the same day, June 23, that the Cabinet endorsed the Syrian-sponsored security plan, a Muslim extremist group claimed responsibility for the kidnaping of a Libyan diplomat and his two bodyguards from a prominent Beirut hotel. Also, an Austrian envoy was killed by an unidentified gunman.
An official of the Christian ''Lebanese Forces'' militia said of the plan, ''We refuse it. If we have to fight the Lebanese Army (as it redeploys throughout the capital), we will.'' The statement was in direct defiance of the Christian members of the new Cabinet.
Each day in Beirut there are acts or threats of violence that one year ago would have made headlines in the world press, but are now accepted as part of Lebanese life. Most of the incidents have been traced to radicals who started as bit-part players in the Lebanese drama and have reached center stage.
The United Nations Relief and Works Agency recently joined the list of victims. It announced that two of its senior foreign workers were evacuated after receiving death threats. The UN agency faces the possibility of suspending its Beirut operation because of the lack of security. This would mean an end to the relief, education, and health services it provides to 90,000 Palestinian refugees.
The list of extremist groups in the Muslim-dominated western half of the capital is growing so quickly it is difficult for diplomats and journalists to keep track. Most are underground cells, unlike the traditional groups that have formal structures and public officials.
Those responsible for the kidnaping of the Libyans, who were released two days later after Syrian intervention, were attached to the ''Sadr Brigade.'' This group of Shiite Muslims campaigns on behalf of their religious leader, Imam Musa Sadr, who disappeared either during or after a trip to Libya five years ago.
Last week, the Shiite ''Amal'' movement announced it had engaged in a three-hour gun battle with the ''Hussein Suicide Squad,'' a previously unheard-of cell of Shiite militants. Amal said the group was responsible for many of the cease-fire violations.
Perhaps the strongest movement is ''Hizbollah,'' or Party of God, a pro-Iranian group of Shiites that used to operate in the eastern Lebanese city of Baalbek but has moved in recent months to west Beirut.
''Hizbollah has repeatedly said it will not stop fighting or agree to a cease-fire with the government,'' a Lebanese official recently told a Beirut paper. ''Our determined policy is to oppose the regime.''
The host of small but dangerous cells has deeply threatened the position of Amal leader Nabih Berri, who is a minister in the new Cabinet. Amal sources say he has stepped up his personal security because of reports that another group, ''Jundallah,'' meaning ''soldiers of God,'' is out to assassinate him, apparently for his moderation and willingness to cooperate with previous rivals.
From east Beirut, the threat to the new government comes in a more conventional form, mainly from ''rejectionists'' in the Lebanese Forces who have undermined the positions of Phalange Party founder Pierre Gemayel and former President Camille Chamoun, both Christians.
On Monday, both Christian members of the Cabinet won backing for the security plan from their separate parties. But an official from the Lebanese Forces, which draws fighters from both, said, ''We will stick to the cease-fire because the population has had enough. But we are not going to give up our (military) positions.''
''The Army collapsed once, and it can happen again,'' he explained. ''So far we have prevented Hizbollah and the other groups from entering (Christian) east Beirut. We do not believe the Army is capable of preventing what would be a disaster.''
Although there is intense pressure on the Christian militia to at least give the plan a chance, there are growing indications that it is prepared to break from the traditional political forces.
Of the two Christian parties' endorsement of the security plan, the Lebanese Forces official commented: ''That is a political statement. But we are the force on the ground.''
The health of Pierre Gemayel, as well as his political strength, has become another cause of concern. He was unable to attend the crucial Cabinet debate on the security plan because of illness. And there is widespread speculation among diplomats about the longevity of the only man who has been able in the past to force extremists to adhere to peace attempts.