U.S. Secretary of State Marco Rubio's proposal for a civilian-led mechanism to replace the United Nations Interim Force in Lebanon (UNIFIL) is emerging as a test of Beirut's ability to enforce State authority in southern Lebanon, with Washington increasingly focused on whether the Lebanese army can prevent Hezbollah from rebuilding its military networks.

U.S. sources told Nidaa al-Watan that the proposal could help break the deadlock between Lebanon's commitments and Israel's security demands, but stressed that changing the composition of the monitoring mission would not address the fundamental problem: the absence of an effective mechanism to detect violations and ensure they are addressed.

Rubio recently said that UNIFIL's successor would not necessarily have to be a military force, suggesting that civilians could oversee a verification mechanism acceptable to both Lebanon and Israel.

The proposal reflects growing U.S. frustration with the existing U.N. model, which maintained a substantial presence in southern Lebanon but lacked the freedom of movement and political backing needed to achieve decisive security results, according to a U.S. diplomatic assessment cited by the sources.

A smaller mission could prove more effective, provided it has sufficient authority to operate without being blocked by local objections, one source said. The significance of Rubio's proposal, therefore, lies less in replacing military personnel with civilians than in shifting the focus from monitoring tensions to verifying whether the parties are fulfilling their commitments.

A source close to the Pentagon said Washington's assessment starts from a fundamental concern: the Lebanese State cannot claim to have restored sovereignty over territory if Hezbollah retains the networks and influence needed to reassert its military presence.

The Lebanese army may establish checkpoints and deploy patrols, but Hezbollah could still maintain communication networks, local influence and intimidation capabilities that would allow it to resume military operations when an opportunity arises, the source said.

Reports that Hezbollah is rebuilding local networks in areas covered by the pilot arrangements have raised doubts about the credibility of claims that the state has established control there.

The source said these reports help explain why Lebanon's international partners do not consider the army's deployment sufficient proof that Hezbollah's organized presence has ended. Publicly released information about army operations has also failed to provide a detailed account demonstrating that the party's command centers, tunnels and weapons depots have been dismantled in those areas.

Against this backdrop, State Department sources described Rubio's proposal as a test for Beirut rather than a ready-made solution. If Lebanon is confident in its control of the south, it should welcome a mechanism capable of independently demonstrating that control.

But if access to suspected sites remains subject to political agreements and every inspection triggers a political crisis, the problem lies in the limits of the Lebanese state's decision-making authority, not in the nationality of the inspectors or the structure of their mission, the sources said.

A State Department spokesperson told Nidaa al-Watan that this does not relieve the Lebanese army of its responsibilities but places the primary responsibility back on the state. The spokesperson criticized statements by Defense Minister Michel Menassa and Army Commander Gen. Rodolphe Haykal, saying they failed to reflect realities on the ground or identify the obstacles preventing Lebanon from restoring its sovereignty, both now and in the future.

France's possible role remains unclear

Rubio said he had discussed UNIFIL's future with French President Emmanuel Macron, leaving open the possibility of a French contribution to the proposed arrangement.

However, a U.S. source close to the National Security Council cautioned that this did not mean an agreement had been reached on the mission's composition, mandate or powers. Washington is still seeking a verification system acceptable to both sides, with its operational details remaining under negotiation.

The source said the main obstacle was political rather than technical. A verification body acceptable to Israel could face resistance in Lebanon, while one selected by Beirut might not provide Israel with the security guarantees it seeks.

The question of who conducts verification is therefore central to the negotiations, as it determines who can access sensitive information and suspected sites, who decides whether commitments have been fulfilled, and who is responsible for reporting violations.

France could help narrow the differences, the source said, but mediation alone cannot resolve them simply by giving the proposed mission a new name.

The real test will be whether both sides accept findings that may not serve their interests. Lebanon, in particular, must be prepared to allow its claims of restored sovereignty to be independently verified rather than invoke sovereignty to prevent inspections, the source added.

Enforcement remains the central challenge

The negotiations are also facing a tight deadline. UNIFIL's mandate expires on Dec. 31, 2026, with its withdrawal scheduled to take place over the following year. G7 foreign ministers acknowledged this week the need to avoid a security vacuum after the force's departure but failed to agree on a replacement.

A source at U.S. Central Command said the proposed arrangement must distinguish between monitoring and verification. While monitoring involves recording developments on the ground, verification requires testing whether specific commitments have been implemented against agreed standards and evidence.

That distinction could give Rubio's proposal practical significance, but the mechanism would remain incomplete without clear procedures for dealing with violations.

The source raised several questions that remain unresolved: If inspectors discover a weapons depot, who will seize it? If they are prevented from entering a suspected building, who will enforce their access? And if Hezbollah threatens mission personnel or the Lebanese soldiers accompanying them, will the state intervene to protect them or resort to political contacts to contain the incident?

These are fundamental questions, not procedural details, the source said. They will determine whether the proposed mechanism becomes a genuine verification system or merely another instrument for managing the state's inability to enforce its authority.

Although civilian inspectors might enjoy greater independence and operational flexibility, they cannot be expected to assume security risks without protection or compensate for the absence of state authority to implement their findings, the military source added.

A U.S. diplomat, meanwhile, stressed that the credibility of the proposed mechanism would also depend on applying the same principle of accountability to Israel.

The trilateral framework is based on reciprocal commitments linking disarmament and proof of Lebanese state control to Israeli redeployment and reconstruction. If Beirut fulfills specific obligations, demands for additional guarantees must not become a pretext for indefinitely postponing Israel's withdrawal, the diplomat said.

Otherwise, the mechanism risks losing its legitimacy in Lebanon and its ability to support the implementation of the broader framework.

For Washington, the issue is no longer simply how to replace UNIFIL but whether a new arrangement can produce results that the existing model failed to deliver. Continued commitments without tangible progress are eroding international willingness to support Lebanon, a U.S. diplomatic assessment suggests.