JERUSALEM — Prime Minister Benjamin Netanyahu of Israel on Tuesday named an old army friend from a rival political party as his new home front minister, amid growing concern here about preparedness for the response to a potential attack on Iran this fall.

The new minister, Avi Dichter, a former head of the Shin Bet — Israel’s version of the Federal Bureau of Investigation — will resign his Parliament seat and quit the centrist Kadima Party to join Mr. Netanyahu’s government. The current home front minister, Matan Vilnai, is becoming ambassador to China.

Mr. Dichter, 59, served with Mr. Netanyahu — and under the command of the current defense minister, Ehud Barak — in the elite special forces unit known as Sayeret Matkal. He spent his career in the Shin Bet before becoming its director in 2000 and left in 2005. The next year, he was elected to Parliament, and named minister of internal security.

“After long internal deliberations, which I haven’t hidden from anyone, I decided to accept the prime minister’s and defense minister’s request,” Mr. Dichter wrote on his Facebook page. “I chose to serve the country as best I can, just as I have in the 42 years since I enlisted in the military.”

The appointment came after several days of newspaper headlines questioning home front preparedness in the case of war with Iran, including the fact that more than 40 percent of Israelis do not have gas masks. On Tuesday, Mr. Netanyahu said his government had invested in the home front “as no previous government has,” adding, “There is much more to do.”

With Mr. Netanyahu and Mr. Barak facing internal opposition from some of their top military and security officials to the notion of a unilateral strike against Iran’s nuclear facilities, some speculated Tuesday that Mr. Dichter’s appointment was an effort to shore up support inside the cabinet. But in February, when he was running for a leadership post within Kadima, Mr. Dichter said Israel should not take military action without the United States.

“Israel is not a superpower,” he said in an article posted on the Israel National News Web site. “We cannot lead the world offensive against Iran. We have to participate, we have to give all kinds of information and intelligence that we have. We need to prepare, just in case nobody plans to do anything, but to lead it will be a total mistake by the State of Israel.”

On Tuesday, a former chief of Israel’s military joined the chorus of security establishment leaders speaking out against the idea of an independent Israeli strike. Amnon Lipkin-Shahak, a retired lieutenant colonel who led the army in the late 1990s, said the United States was “much more capable” of eliminating the Iranian threat, and “we shouldn’t rush” to act before the American presidential election.

“I assume that the decision makers have the same information as the heads of the security establishment,” Mr. Lipkin-Shahak said.

“I ask myself, how is it that the security officials and the politicians can arrive at such different conclusions?” He added, “I have complete faith in the security officials and give a lot of weight to their opinion.”

Meanwhile, the spokesman for Iran’s Foreign Ministry on Tuesday played down the threats of an Israeli strike as “hollow and baseless.”

“Even if some officials in the illegitimate regime want to carry out such a stupid action,” said the spokesman, Ramin Mehmanparast, referring to Israel, “there are those inside who won’t allow it because they know they would suffer very severe consequences from such an act.”

The Iranian Students News Agency reported that another official, Defense Minister Ahmad Vahidi, said Israel “definitely does not have what it takes to withstand Iran’s might and will.” Thomas Erdbrink contributed reporting from Tehran. (Copyright 2012 The New York Times Company 08/15/12)