WASHINGTON - There´s "no credible or specific" evidence of an Iranian terror plot targeting the U.S., but officials are closely tracking the threat, the country´s top homeland security official said Wednesday.

After failed plots targeting a Saudi diplomat in Washington and Israelis in India, Thailand and the Republic of Georgia, the NYPD´s intelligence boss said this week that Iran is essentially No. 1 among threats to the Big Apple.

On Capitol Hill to pitch her agency´s 2013 budget, homeland security secretary Janet Napolitano faced questions on Iran from House Homeland Security Committee Chairman Pete King (R-L.I.) and colleagues.

King voiced concerns that Iranian proxy Hezbollah - which bombed the Israeli embassy and a Jewish community center in Buenos Aires during the 1990s - might target U.S. synagogues.

Napolitano said there´s no proof Iran is poised to strike, but called the rogue regime "a threat that bears watching."

DHS hosted a conference call with top U.S. Jewish organizations last week to share its threat assessment, Napolitano told lawmakers.

DHS and partners like the FBI "are constantly monitoring their activities around the world," said Napolitano, a New York native and former federal prosecutor.

A blast in Bangkok linked to Iranians involved "sticky bombs" attached to vehicles, which experts say could be payback for the assassination of nuclear scientists Tehran blames on Israel.

But Thai police say they arrested two Iranian men after the accidental explosion, including one whose legs were blown off. Two more people were being sought.

In the Indian incident, which injured a diplomat´s wife going to pick up her kids, a bomb was attached to a minivan with magnets - the same type of devices used to kill several Iranian scientists.

The son of one appeared with Iranian President Mahmoud Ahmadinejad on Wednesday to announce a new advance in the country´s nuclear program.

A defiant Ahmadinejad inserted what he claimed was the first domestically produced fuel rod into a research reactor.

Last month Director of National Intelligence Gen. James Clapper told Congress that Iran, cornered on the world stage over its secretive nuclear program and thinly veiled threats to Israel, is more willing to risk attacks on U.S. soil.

NYPD Director of Intelligence Analysis Mitchell Silber described last year´s plot targeting Saudi Ambassador Adel al-Jubeir as a "Wow" moment indicating Tehran is willing to risk war with the U.S. or Saudi Arabia.

Iran´s Qods Force intelligence service tasked a Texas man with hiring a Mexican drug cartel to target al-Jubier by bombing a Washington restaurant with no regard for civilian casualties, prosecutors charge.

The suspect´s Mexican cartel contact happened to be a U.S. informant. With Rocco Parascandola and News Wire services (© Copyright 2012 NYDailyNews.com. 02/16/12)