When Does US Use or Threaten Force?

The United States is backing a NATO threat of airstrikes against Serb forces in Kosovo unless Yugoslavia meets NATO terms by Friday. But the US has not always threatened force elsewhere, even when conditions were similar.

* In late 1994, Russian forces cracked down on breakaway Chechnya, leveling much of the Chechen capital of Grozny and carrying out a war that killed at least 80,000 people over the next two years. The US regarded this as an internal Russian matter.

* In the aftermath of the 1991 Gulf War, President Bush promised support to Kurds in northern Iraq in any uprising against President Saddam Hussein. With no US help, the uprising failed. The US, Britain, and France set up a "safe haven" in northern Iraq, which was rolled over by Saddam in 1996.

* A debacle in Somalia (detailed below) led to US nonintervention during the 1994 genocide, mainly against Tutsis, in Rwanda, in which some 800,000 were killed. (US forces did step in after the genocide to assist Hutu refugees in Zaire.)

* In 1997, the US did not intervene when rebels overthrew longtime US ally Mobuto Sese Seko in Zaire (now Congo), allegedly carrying out atrocities in the process.

* The US has spoken out firmly, but not acted, in disputes between China and Taiwan - and to a lesser degree, China and Tibet.

* The US has also stayed out of Algeria, where a military government has been locked since 1992 in conflict with Islamic extremists at a cost of some 70,000 lives.

Where the US has acted:

At times, strikes have been retaliatory, as when the US hit Libya in 1986 after linking that state to a terrorist bombing that killed US servicemen in Berlin, and as with Afghanistan and Sudan after recent embassy bombings in East Africa.

In other cases the US has moved in with ground troops to protect its interests - including the cause of democracy. Such examples include Grenada (1983), Panama (1989), and Haiti (1993-1994). Also:

* In 1992, the US launched an intervention to overcome efforts by Somali warlords to thwart distribution of food aid in the rebel south. This devolved into military conflict and a US pullout.

The Somalia case had impact in the region: Leaders in Sudan - who had been preventing food aid from getting to rebels in the south - reversed that policy for a time in anticipation of similar intervention.

* In 1995, the US led NATO airstrikes to break the Bosnian Serb seige of Sarajevo, leading to the end of that war and to the Dayton accords.