jerusalem -- An Israeli airstrike killed four Palestinian militants in the Gaza Strip and a rocket exploded near a home Sunday in southern Israel, continuing a surge of fighting that has threatened to unravel a 5-month-old cease-fire.
Israeli Prime Minister Ehud Olmert told a weekly Cabinet meeting that he had asked his security chiefs to present proposals for military action if necessary to halt rocket fire from the Gaza Strip.
In Gaza, a spokesman for the Popular Resistance Committees, whose members were killed in the airstrike, warned that Israel would "bear the consequences and responsibility" for what he called its decision to end the cease-fire.
The group is allied with Gaza's Hamas rulers.
Violence across the border broke out Nov. 4, when Israeli forces crossed into the Gaza Strip to destroy what the army said was a tunnel dug by Hamas in a plan to seize an Israeli soldier. Six gunmen were killed in the raid, and militants responded with volleys of mortar shells and rockets into Israel.
Fifteen militants have been killed in clashes over the last two weeks, and according to an Israeli army tally, militants have fired about 120 rockets and mortar shells.
The four militants were killed Sunday in the northern Gaza Strip as they were preparing to fire a rocket, the army and Palestinian medical officials said.
A rocket fired later at the southern Israeli town of Sderot exploded near a house, and a resident sustained minor injuries.
Israel has sealed Gaza's border crossings since the start of the latest fighting, barring food distributed by the United Nations to 750,000 needy Gazans and fuel supplies to a Gaza City power plant, leading to extensive blackouts.