Before dawn on Tuesday, dozens of men dressed in black carrying hand-held radios fanned out across the Lebanese capital, according to the local media. They were spotted on major roads from downtown Beirut to the airport. The men were unarmed but organised and disciplined.
By the time the men disappeared anxious parents rushed to pull their children out of school. Beirutis spent the rest of the day on edge. The media labelled the incident a "show of force" by Hizbollah, the Shiite political party and militia that brought down the Lebanese government last week. It was an innocuous yet menacing display by Lebanon's most powerful military force.
A day earlier, an international prosecutor issued the first indictment in a case that has set off Lebanon's latest political crisis: a United Nations tribunal investigating the assassination of the former Lebanese prime minister, Rafik Hariri, in 2005. The charges remain sealed but Hizbollah's leaders have acknowledged that they expect several members of the movement to be indicted.
For months, Hizbollah has tried to discredit the tribunal, casting doubt on its evidence and witnesses. The group has also pressured Saad Hariri - the slain leader's son who was named prime minister of a national unity government in November 2009 - to end Lebanon's cooperation with the tribunal and publicly reject its findings. Backed by the United States and Saudi Arabia, Mr Hariri has refused to disavow the tribunal.
As the indictment neared, Hizbollah and its allies withdrew from the cabinet on January 12, leading to the government's collapse. Mr Hariri became a caretaker prime minister, and the Lebanese president Michel Suleiman is poised to begin consultations with parliamentary leaders on Monday to appoint a new premier. Mr Hariri's supporters, who hold a slight majority in parliament, vowed that they will only accept his return as prime minister.
No matter what political faction they support, Lebanese wondered after Hizbollah's walkout from the government: "What's next?" The militia provided an answer with its "show of force" on Tuesday. While Hizbollah's media office coyly refused to confirm that the group had dispatched the black-clad men, one official told a Lebanese newspaper: "This was just a small message to show that the time for talk is over."
Hizbollah's message was clear: the tribunal has international support and the authority to issue indictments, but the real power lies on the streets of Lebanon. Hizbollah dominates that arena with its overwhelming military superiority. The group was also sending a signal to Mr Hariri: support from the US and other western powers will not change the reality on the streets.
How did Hizbollah gain this military dominance? When Lebanon's 15-year civil war ended in 1990, all of the country's militias were disarmed. But Lebanese leaders allowed Hizbollah to keep its weapons as a "national resistance" against the Israeli occupation of southern Lebanon, which continued until May 2000. After the Israelis withdrew, many Lebanese asked why the group did not disarm and become a strictly political movement. Hizbollah insisted that its mission of resistance was not over because Israel was still occupying a strip of land, Shebaa Farms, at the intersection of Israel, Syria, and Lebanon. (The United Nations later determined that the area is Syrian territory, not Lebanese.)
In May 2008, Hizbollah proved its military might when it dispatched hundreds of heavily armed fighters into the largely Sunni areas of West Beirut. They quickly routed Sunni militiamen, seized their political offices and shut down media outlets owned by Mr Hariri. Then Lebanon was in the midst of another long political stalemate, and Hizbollah acted in response to a government decision outlawing the militia's underground fiber-optic communication network.
The tribunal's prosecutor, Daniel Bellemare, sent the first indictment to a pretrial judge on Monday, who will decide within six to 10 weeks if there is enough evidence to go trial. At that point, the indictment would become public and UN officials would formally request that Lebanese authorities hand over the named suspects. The judge could also reject the indictment or request more evidence and the prosecutor could issue new indictments as the investigation continues.
In a speech on Sunday, the Hizbollah leader Hassan Nasrallah vowed that the group would defend itself against any accusation of involvement in Hariri's murder. "We will act to defend our dignity, our existence and our reputation," he said, adding: "The findings of the international tribunal are decided in Israel and Washington."
In the past, Mr Nasrallah had vowed to "cut the hands" off from those who try to arrest Hizbollah members. While he tried to strike a more conciliatory tone on Sunday, he also warned that once the tribunal's charges are made public, it would be "too late" to reach a deal to save Lebanon.
Even if the next Lebanese government ends cooperation with the tribunal and cuts off its funding, the court's work could continue if other countries provide funds. But it is symbolically important for Hizbollah to convince Mr Hariri to disavow the tribunal. Hizbollah portrays itself as a pan-Islamic movement committed to fighting Israel. If the Shiite group is accused of killing Lebanon's most prominent Sunni leader, then it would become just another sectarian militia in the eyes of the wider Arab and Muslim worlds. Regardless of those regional calculations, Hizbollah remains the most powerful force in Lebanon and has the guns to guarantee that dominance.
Mohamad Bazzi is a journalism professor at New York University and an adjunct senior fellow at the Council on Foreign Relations