Fighting in the Syrian capital of Damascus raged for a third straight day, the most sustained challenge to the seat of power of President Bashar al-Assad. The Syrian government has escalated their response as a result:

Activists in the northern Damascus suburb of Qaboun said the Syrian forces were backed by helicopter gunships, an apparent hardening of the government’s response to urban fighting that has spread toward central Damascus and the seat of President Bashar al-Assad’s power.

Videos posted by antigovernment activists showed night scenes of gunfire and helicopter noise as well as daytime images of what was said to be helicopter gunships flying over the capital. There were indications on Tuesday that the rebel fighters, confident of support in some areas of Damascus, were moving into new neighborhoods to test the government’s response.

“The heaviest clashes are going on in Al-Midan and the neighboring areas,” said a spokesman for an activist group in Damascus. “Regime forces are threatening to bombard the whole area and telling civilians to evacuate their houses.”

This is what civil war looks like. And this was inevitable amid an impotent international response. The Syrian uprising began peacefully, with chants and marches after Friday prayers. The regime carried out excessive violence for months before the protesters decided to mobilize a rebel force and arm themselves. That space of time was ill-used by the international community, and we’re now seeing the fruits of that – a civil war which has killed at least 17,000 Syrians, with the prospect of many more dead in the coming weeks and months. The international deadlock continues, meanwhile, with Russia accusing Western powers of blackmail to get them on the side of economic sanctions for the Assad government.

A British draft resolution backed by the West and many Arab countries links the extension of the monitoring mission, first approved in April, to a 10-day deadline for Mr. Assad to implement the six-point plan he accepted in March. It includes an immediate cease-fire and steps toward a political transition.

Failing that, the resolution would invoke Chapter 7 of the United Nations Charter, which allows for punitive measures, like economic sanctions, and ultimately military action to enforce Security Council demands.

The Russians are adamantly opposed. They feel they were deceived into accepting a Western plot for leadership change in Libya when force was used there under Chapter 7 last year.

“To our great regret, there are elements of blackmail,” Mr. Lavrov said. “We are being told: if you do not agree to the resolution under Chapter 7 of the U.N. Charter, then we shall refuse to extend the mandate of the monitoring mission in this country.”

In fact, Russia continues to perform maintenance work on Syrian armaments and helicopters, under existing contracts.

Activists are hopefully describing the clashes in Damascus as the “beginning of the end,” and surely they are significant, as the capital has not experienced violence on this scale before. But this is the road that has been traveled now. I don’t see any alternative option but a long and bloody fight for control of Syria. Indeed, even some activists described the fighting as a test of the power of the regime. These tests will continue for a long time.