I know from personal involvement that the devastating invasion of Gaza by Israel could easily have been avoided.

After visiting Sderot last April and seeing the serious psychological damage caused by the rockets that had fallen in that area, my wife, Rosalynn, and I declared their launching from Gaza to be inexcusable and an act of terrorism. Although casualties were rare (three deaths in seven years), the town was traumatized by the unpredictable explosions. About 3,000 residents had moved to other communities, and the streets, playgrounds and shopping centers were almost empty. Mayor Eli Moyal assembled a group of citizens in his office to meet us and complained that the government of Israel was not stopping the rockets, either through diplomacy or military action.

Knowing that we would soon be seeing Hamas leaders from Gaza and also in Damascus, we promised to assess prospects for a cease-fire. From Egyptian intelligence chief Omar Suleiman, who was negotiating between the Israelis and Hamas, we learned that there was a fundamental difference between the two. Hamas wanted a comprehensive cease-fire in both the West Bank and Gaza, and the Israelis refused to discuss anything other than Gaza.

We knew that the 1.5 million inhabitants of Gaza were being starved, as the U.N. special rapporteur on the right to food had found that acute malnutrition in Gaza was on the same scale as in the poorest nations in the southern Sahara, with more than half of all Palestinian families eating only one meal a day.

Palestinian leaders from Gaza were noncommittal, claiming that rockets were the only way to respond to their imprisonment and to dramatize their humanitarian plight. But top Hamas leaders in Damascus agreed to consider a cease-fire in Gaza only, provided Israel would not attack Gaza and would permit normal humanitarian supplies to be delivered to Palestinian citizens.

After extended discussions with those from Gaza, these Hamas leaders also agreed to accept any peace agreement that might be negotiated between the Israelis and Palestinian Authority President Mahmoud Abbas.

We relayed this information to the Egyptians, and they pursued the cease-fire proposal. After about a month, the Egyptians and Hamas informed us that all military action by both sides and all rocket firing would stop on June 19, for a period of six months, and that humanitarian supplies would be restored to the normal level that had existed before Israel's withdrawal in 2005 (about 700 trucks daily).

We were unable to confirm this in Jerusalem because of Israel's unwillingness to admit to any negotiations with Hamas, but rocket firing was soon stopped and there was an increase in supplies of food, water, medicine and fuel. This fragile truce was partially broken on Nov. 4, when Israel launched an attack in Gaza to destroy a defensive tunnel being dug by Hamas inside the wall that encloses Gaza.

On another visit to Syria in mid-December, I made an effort for the impending six-month deadline to be extended. It was clear that the preeminent issue was opening the crossings into Gaza. Representatives from the Carter Center visited Jerusalem, met with Israeli officials and asked if this was possible in exchange for a cessation of rocket fire. The Israeli government informally proposed that 15 percent of normal supplies might be possible if Hamas first stopped all rocket fire for 48 hours. This was unacceptable to Hamas, and hostilities erupted.

Seventeen mosques, the American International School, many private homes and much of the basic infrastructure of the small but heavily populated area have been destroyed. This includes the systems that provide water, electricity and sanitation. Heavy civilian casualties are being reported by courageous medical volunteers from many nations, as the fortunate ones operate on the wounded by light from diesel-powered generators.

The hope is that when further hostilities are no longer productive, Israel, Hamas and the United States will accept another cease-fire, at which time the rockets will again stop and an adequate level of humanitarian supplies will be permitted to the surviving Palestinians, with the publicized agreement monitored by the international community. The next possible step: a permanent and comprehensive peace.

Jimmy Carter was president from 1977 to 1981. He founded the Carter Center, a nongovernmental organization advancing peace and health worldwide, in 1982. He wrote this commentary for The Washington Post.