The radical Islamic group, Hamas, which now heads the Palestinian Authority, has set off a political storm by appointing a top militant to a security post.  There has been harsh reaction from both Israel and the Palestinian president.

Israel is threatening to step up military action against Hamas, after the new Palestinian government appointed Jamal Abu Samhadana to set up a new police force.

Samhadana is on Israel's most wanted list, and the army says he is responsible for many deadly attacks on Israelis. He is also believed to be the mastermind of an attack on a U.S. diplomatic convoy in Gaza in 2003 that killed three American security guards.

Israel's deputy defense minister, Ze'ev Boim, said the appointment of Samhadana shows that Hamas is establishing a terrorist regime.

"We will settle accounts with this murderer," Boim told Israel Radio. "This appointment will not buy him immunity."

One former security chief went further, saying the entire Hamas Cabinet could be targeted for assassination. 

Hamas spokesman Razi Hamed defended the appointment, also on Israel Radio.

Hamed said Samhadana was appointed to restore law and order to the chaotic Palestinian streets, which he described as a top priority.

But Israel was not the only one complaining. Palestinian President Mahmoud Abbas, of the more moderate Fatah party, said he would cancel the appointment because it is illegal. The dispute points to a growing power struggle between Mr. Abbas, who supports peace talks with Israel, and Hamas, which is committed to the destruction of the Jewish state.

So, Hamas is facing pressure from all sides. Israel is threatening military action, Mr. Abbas is trying to curb the powers of the new government, and the U.S. and Europe have imposed crippling economic sanctions.

But Hamas is defiant. Samhadana, the newly appointed security chief, said he would not halt his involvement in attacks against Israel.