Tensions are escalating between Israel and Palestinian militants in the Gaza Strip.
Israel has filed a protest with the United Nations after Palestinian militants in Gaza fired rockets and mortar shells across the Israeli border. In a letter to U.N. Secretary-General Ban Ki-moon, Israel said that some of the mortar shells contained white phosphorous, which causes severe burns.
The use of phosphorous against civilians is banned under international law. Israel admitted to using white phosphorous during the Gaza War two years ago, and the U.N. and human rights groups said that amounted to a war crime.
Israel responded to the latest attacks with three air strikes on Gaza. The escalation has raised concern among Israeli communities on the Gaza border, which have been mostly quiet since the Gaza War.
But Zvika Greengold, the mayor of the southern Israeli town of Ofakim, said times are changing. He told reporters that the recent quiet is deceiving and that Israelis on the border are "sitting on a tinderbox."
A coalition of militant Palestinian groups called the Popular Resistance Committees claimed responsibility for the attacks. They said it was retaliation for Israel's targeted killing of two leaders of the al-Qaida-linked Army of Islam in a Gaza air strike on Wednesday. Israel said the group was planning to kidnap Israelis in Egypt's Sinai Peninsula and use them as bargaining chips for the release of Palestinian prisoners.
Another Gaza militant group affiliated with al-Qaida, Ansar al-Sunna, issued a warning to Israel in Hebrew. It said the jihad and rocket attacks will continue, and Israelis will not have security until they leave Palestine.
In its letter to the U.N., Israel warned that is prepared to take tougher military action to stop the cross-border attacks.
Some information for this report was provided by AP, AFP and Reuters.