Three bombs exploded today at a U.S. air defense base in southern West Germany, destroying three radar units in the latest in a wave of terrorist attacks on American military installations.

The blasts, which occurred shortly after 6 a.m. (midnight EDT) when few soldiers were on duty, inflicted no injuries but probably more than $1 million in damage, according to a spokesman at U.S. Army headquarters in Heidelberg.

Officials at the federal prosecutor's office in Karlsruhe said they suspected that militants of the left-wing Red Army Faction carried out the bombings. It marked the ninth time this year that U.S. or North Atlantic Treaty Organization facilities have been attacked in West Germany.

The bombings underscored the logistical difficulties in protecting scattered U.S. military facilities in West Germany from sabotage. Army officials said that only 12 men were on duty at the time of the blast and the area had been inspected an hour earlier, but this did not inhibit the terrorists from reaching the radar sites.

West German police said the saboteurs gained access by cutting the chain-link perimeter fence in two places. Investigators found graffiti near the scene of the blasts that extolled jailed faction members and denounced "imperialist wars."

The base, near Nohfelden in the state of Saarland, is manned by about 100 American military personnel of the 32nd Army Air Defense Command. The soldiers are responsible for operating Hawk nonnuclear ground-to-air antiaircraft missiles.

Sgt. Bob Lentner, a spokesman for the U.S. Army in Heidelberg, said of today's attack, "There were three blasts that destroyed three mobile radar sets mounted on trailers."

West German security officials have become worried about a more brutal terrorist offensive since a car bomb exploded at the U.S. Rhein-Main Air Base in Frankfurt Aug. 8, killing two Americans and wounding 20 others. The Red Army Faction claimed responsibility for the bombing as well as the earlier murder of an American soldier, whose identity card the attackers used to enter the air base.

Police observed later that, whereas the faction's previous assaults had been aimed at senior military commanders, industrialists and bankers, the terrorists had opted for killing or maiming low-ranking soldiers and bystanders.

The prosecutor's office also said that it was hunting three suspected Red Army Faction leaders for the murder of a West German arms industry executive in Munich in February. It named them as Barbara Meyer, Horst Meyer and Eva Haule-Frimpong, Reuter reported .

Antiterror experts have warned that the faction, which went into decline in the late '70s with the arrest of its key leaders and confiscation of its funds and arms, appears to have rebuilt its urban guerrilla force through recruits drawn from thousands who share the group's anti-NATO, class-warfare objectives.

The faction also has refurbished its arsenal with stolen explosives and high-powered rifles and accumulated well over $1 million from bank robberies. It also has strengthened cross-border cooperation with other groups in Europe's terrorist underground, including France's Direct Action and Belgium's Fighting Communist Cells.

Security specialists said it appeared that the faction had attracted new adherents to its violent tactics from among those antinuclear activists disappointed with the failure to stop deployment of advanced missiles in West Germany.

They said that several recent bombings, which damaged property but not people, were probably conducted by the new recruits. It is believed that only the more experienced, hard-core Red Army Faction members have carried out the bloodier attacks.

On Monday, two bombs went off at the offices of computer companies in Dortmund and Hamburg. Revolutionary Cells, a group known to have connections with the faction, said it exploded the bombs.

A radio antenna was also damaged Aug. 15 in a bomb attack on a U.S. supply depot by a group seeking the release of jailed Red Army Faction guerrillas.