Updated

GAZA CITY, Gaza Strip -- The militant Islamic Hamas rulers of Gaza warned Israel Saturday that it will escalate hostilities against Israel if tensions don't subside along the Gaza-Israel border, and the shadowy leader of its military wing vowed to make Israel "disappear."

Hamas spokesman Abu Obeida said the group would respond aggressively to Israeli attacks. He said Israel is "playing with fire."

A recent flare-up along the border has threatened the calm that has largely held since Israel's bruising invasion of Gaza two years ago aimed at stopping years of Palestinian rocket fire. About 1,400 Palestinians were killed during the 3-week war, including hundreds of civilians.

Israel was roundly condemned for its late 2008 incursion, though it followed the firing of thousands of rockets by Gaza militants at southern Israel.

Over the last week, Gaza's militants fired 30 rockets into southern Israel, lightly wounding a 15-year-old girl. Israel hit back with multiple airstrikes aimed at Hamas facilities, killing a Palestinian and wounding several others.

Early Saturday, Israel bombed what the military said was a Gaza "terror training facility" and a weapons smuggling tunnel under the Gaza-Egypt border. Hamas said there were no casualties.

The sudden surge of cross-border violence has led to speculation that Israel might mount another invasion, but there were no signs on the ground that such a move was near.

On Saturday, Mohammed Deif, the leader of Hamas' armed wing broke a long silence with a vow to make Israel "disappear." Hamas ideology laves no room for a Jewish state in an Islamic Middle East, but some relatively pragmatic Hamas leaders have indicated they would accept a Palestinian state in the West Bank, Gaza Strip and east Jerusalem as a temporary step if approved in a Palestinian referendum.

In a statement to mark the 23rd anniversary of founding of Hamas, Deif addressed Israel directly. "You are going to disappear," he wrote in a newsletter put out by the military wing, "no matter how long it takes ... we will not raise the white flag to you as long as there is one Muslim on this planet."

The Israeli military refused to comment about either Hamas statement. Israel holds Hamas responsible for all violence toward Israel from Gaza, though much of the rocket fire has been carried out by more radical splinter groups.

Deif is on Israel's most wanted list for his part in planning suicide bomb attacks that killed Israelis. He has been severely wounded twice in Israeli assassination attempts and lives in hiding.