Grinding civil war in Libya, a state-organized bloodbath in Syria and troubling stumbles in Egypt’s march to democracy dim the luster of Arab revolts that began the year in glory. This Arab summer is a political season of reaction and reversal.

But it is not a moment to despair or to overlook the longer-term meaning of the sweeping change 2011 has brought to the Middle East. Besides, we are in too deep to wash our hands and pretend we can stand aside while dictators have their culturally appropriate way.

Americans and Arabs have been brought into jarring contact and sometimes into the line of fire to an extent that was once unimaginable and probably unwanted by either side. Operation Desert Storm in 1991; the Sept. 11, 2001, attacks on the U.S. homeland by Arab radicals; the 2003 invasion of Iraq; and this year’s Arab revolutions have all played a part in this intensified interaction.

The upheaval that began in Tunisia seven months ago turned a spotlight on the spread of Western information technology and social networking habits into the once-isolated city-states of the Arab world. Less visible has been what I think of as a constant lesson of colonial history: Be careful whom you would invade or dominate. The people you attempt to rule will mark you as surely as you will imprint yourself on them and their institutions, even if it takes much longer to surface.

Propagandists for Libya’s Moammar Gaddafi and Syria’s Bashar al-Assad pretend that Islamic fundamentalism brings their citizens into the street to demand an end to their blood-stained dictatorial rule. Nothing could be further from the truth. Western ideas and technology have had much more to do with sparking the revolts that have undermined would-be dynastic dictatorships in Egypt, Libya and Syria, and the destruction of the thug state that had emerged in Tunisia — all significant accomplishments in themselves.

The governments that make up the Arab League earned the world’s respect in March by condemning Gaddafi’s threats to slaughter Libyan civilians wholesale. They have brought shame on themselves by watching Assad’s savage campaign to exterminate his political opponents in Syria in silence until Sunday. Even then, they stopped short of clearly condemning Assad in a statement that expressed concern and distress over Syria’s violence. The March resolution turns out to have been more personal — aimed at Gaddafi, not bloody repression — than it was principled.

This retreat from international humanitarian standards greatly hampers all other international efforts to pressure Damascus. Moral indignation by outsiders, to say nothing of military action like that undertaken by NATO in Libya, best succeeds when there is local political cover and cooperation.

Official Arab disapproval has not been forthcoming even as Bashar, the London-trained ophthalmologist who once charmed Westerners into believing he was a reformer, has acted exactly as did his ruthless father, Hafez, the flinty air force general who seized power in 1970.

But the son’s Syria is not the isolated redoubt the father ruled. Hafez systematically razed much of the town of Hama in 1982 before word filtered out to Beirut that an estimated 20,000 people had been massacred there. Today, tanks shelling Hama’s streets — and Syrian troops occupying mosques — are shown on al-Jazeera and other satellite television networks as quickly as cellphone video can be uploaded by a sophisticated network of incredibly brave Syrian dissidents.

Such imagery must over time erode the legitimacy of the Arab (and Iranian) rulers who offer Assad succor. Even these police states are vulnerable to the virus of modern communication. U.S. policy should continue to focus on drawing ever-brighter lines of condemnation around the Syrian ruler and those who support him, including through the imaginative use of economic pressure.

The United States and the European Union must also stay involved in Egypt’s unfinished revolution, which teeters between springtime glory and midsummer dishonor as it engages in political exorcism. The rush to try an enfeebled Hosni Mubarak on murder charges betrays a country so uncertain of managing its future that it hurries to revise its past, by making one man responsible for all the country’s ills. Mubarak deserves to answer to justice — but not on a commissar’s political timetable.

Moreover, Egypt’s pro-democracy activists and human rights advocates are increasingly caught up in dragnet arrests and prosecution before assembly-line military tribunals. A whiff of counterrevolution wafts through the Cairene air.

We are at a fitful intermission, not a final curtain, for the new Arab revolutions. We have seen how information technology can provide a spark that sets afire the kindling of economic and social distress. That turns out to have been necessary, but not sufficient, to transform societies long exploited by their rulers. Much more work and understanding by both Arabs and Americans is required.

The writer is a contributing editor to The Post. His e-mail address is