Patience among Israeli leaders is wearing thin with Palestinian militants who have fired a barrage of rockets into Israel in recent days, leading some in the Middle East to conclude that an incursion into the troubled Gaza Strip could be only days away.

On Friday, a militant-fired rocket failed to reach its Israeli target and killed a pair of Palestinian cousins -- aged five and 12 -- who were inside a house in the northern Gaza Strip.

No one claimed responsibility for the attack that also injured three other children.

The Israeli military said 13 such rockets landed in Israeli territory by Friday evening, but no Israelis were reported injured.

These attacks have members of the Israeli government talking tough about how they plan to stop the violence.

"If Hamas insists on shooting missiles, on shooting hundreds of missiles over a period of a few days as they have just done, then it will leave us no choice but to do everything we can to remove this threat," Yigal Palmor of the Israel Foreign Ministry said.

As Foreign Minister Tzipi Livni put it: "Hamas needs to understand that our aspiration to live in peace doesn't mean that Israel is going to take this kind of situation any longer. Enough is enough."

On Friday, however, the Israeli government opened its Gaza border allowing for humanitarian aid to be delivered to the region.

Israeli cabinet minister Binyamin Ben-Eliezer said the aid was meant to show Palestinian civilians that they are not the enemies of Israel.

"We are sending them a message that the Hamas leadership has turned them into a punching bag for everyone," he said Friday, when speaking to Israeli Radio."It is a leadership that has turned school yards into rocket-launching pads. This is a leadership that does not care that the blood of its people will run in the streets."

While there were no signs that Israel had plans for an immediate response, its government signaled on Thursday that the country's military was capable of launching a counter-attack against the militants behind the attacks.

The Associated Press reported that unnamed military officials said an offensive would open with targeted air strikes against the rocket launching sites, and would then move into a full-scale land invasion into Gaza.

But it wasn't immediately clear when an invasion, if at all, would take place. Not only was bad weather hampering any potential operation, but Israel faces the prospect of heavy casualties if an invasion is launched.

A large operation is also complicated by upcoming elections, which occur in February. Livni is hoping to become prime minister after winning leadership of the centrist Kadima Party earlier this year. Her chief rival is former prime minister Benjamin Netanyahu, head of the Likud party.

Any invasion would also erase Israel's historic 2005 Gaza pullout and put the army face to face with Islamic Hamas fighters, who won power in 2007 from Palestinian President Mahmoud Abbas.

With files from The Associated Press