DAKAR, Senegal — Tear gas fired on hundreds of demonstrators in Togo. Mass arrests of protesters in Guinea. Guerrilla assaults against police officers and soldiers in Ivory Coast. Rock- and bottle-throwing antigovernment militants suppressed with force in Gabon.

It has been a hot summer in the capitals of Africa’s west coast. Authority has been challenged — in the streets, by ambush at night, with stones or guns in broad daylight — and the governments have struck back with their customary heavy hand. Regardless of whether those governments are considered legitimate by outside observers and governments, as in the case of Guinea and Ivory Coast, or suspect, as with Togo and Gabon, it has been a summer of siege.

Political evolution on the continent’s western side is often a series of eruptions: order appears to be established, and then the volcano explodes again. In Togo and Gabon, the levers of power have long seemed immutable, dominated by the same families for decades. In Guinea and Ivory Coast, both on the mend after years of upheaval, democratic order seemed to arrive at last only recently. But all of these nations bubble with uncertainty beneath the surface. Western donors and officials who visit the West African capitals to offer congratulations on stability — the new World Bank president was in Abidjan, the Ivorian commercial capital, last week — should be warned: their compliments may be premature.