Take this with the customary grain of salt that accompanies most breaking reports from urban-warfare theaters, and perhaps especially in Tripoli, where Moammar Qaddafi’s sons are either in custody or acting as tour guides for the capital of Libya.  Rebels now report having reached Qaddafi’s compound, which means that either the regime will fall shortly, or … not:

 Libyan rebels battled on Tuesday around Muammar Gaddafi’s headquarters, where a son of the veteran leader had emerged overnight to confound reports of his capture and to rally cheering loyalists for a rearguard fightback.

NATO jets flew in support of the rebels, who said they were trying to break into Gaddafi’s fortified Bab al-Aziziya compound. His son and presumed heir Saif al-Islam had earlier told a crowd that his father was well and still in Tripoli.

Heavy smoke drifted across the city center and a Reuters correspondent at a government-controlled hotel near the sprawling compound heard heavy gunfire and explosions. NATO declined comment on whether it had struck Bab al-Aziziya.

“The revolutionaries are trying to get in through the Old Gate on the western side,” rebel fighter Muftah Ahmad Othman told Al-Arabiya television from Tripoli. “If they’re successful, the fighting will move inside the compound.”

It’s really just a matter of time before the compound falls, unless Qaddafi can find a way to get a relief column into Tripoli to break the siege.  Al-Jazeera says the rebels have complete control of the perimeter now, and while regime forces are still fighting, they’re not making any significant gains.  NATO warplanes are attacking the compound at Bab al-Azizya, and will likely continue until they can no longer do so without endangering rebel forces when they finally break into the compound.  Reuters reports that some have already broken through, although there doesn’t seem to be any independent confirmation.

So what about the chemical weapons Qaddafi has stored for desperate last stands?  The US says they are keeping a close eye on storage sites, but since we don’t have troops on the ground, we’re not in position to do much about it if any forces decide to use them.  It’s hard to imagine Qaddafi deploying them for close combat, but he’s not exactly known for his rationality, either.

Here’s a question: What if the rebels finally seize Bab al-Azizya and Qaddafi’s not there?  The US still thinks Qaddafi’s in Tripoli, and the presence (and sudden freedom) of his sons would suggest we’re correct.  But if the dictator has moved his flag outside of Tripoli, he won’t last long regardless — and might be thinking about taking his leave of Libya permanently.

Update: The BBC says that rebels have taken control of the compound:

Libyan rebels have taken over Col Muammar Gaddafi’s compound in Tripoli, one of the final areas under the Libyan leader’s control. …

Footage from Sky News showed gangs of rebels gathered about 50m (164ft) from the compound dressed in civilian clothes, some armed with rifles, others unarmed. The sound of shells exploding could be heard nearby.

Later reports said hundreds fighters had breached one of the gates of the compound, and that gangs were inside the compound firing guns into the air to celebrate.