The Israeli military said on Tuesday that it resumed its airstrike campaign in the Gaza strip after Hamas militants did not abide by a de-escalation proposal brokered by Egypt.

Israel held its fire for six hours after agreeing to the Egyptian plan. Hamas continued its rocket attacks on Israel, to which the Jewish state responded by resuming its airstrike campaign, the Associated Press reported. Israel "has resumed operation activities," military spokesman Lt. Col. Peter Lerner told the AP.

A military spokeswoman also confirmed the Israeli attacks to Reuters, saying, "Israeli forces are attacking again."

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    Smoke from rockets fired from Gaza City are seen after being launched toward Israel, on July 15, 2014. US Secretary of State John Kerry warned of the 'great risks' that the violence between Israel and the Gaza Strip could spiral out of control. Photo: THOMAS COEX/AFP/Getty Images
  • Israeli tanks
    Israeli tanks and armored personnel carriers (APCs) are seen at a staging area outside the central Gaza Strip July 15, 2014. Photo: Reuters

The six hours of de-escalation was part of a cease-fire plan proposed by Egypt to end the weeklong fighting between Israel and Palestinian militants. Israeli Prime Minister Benjamin Netanyahu said earlier that Israel would strike back if Hamas didn't accept the proposal.