* Moshe Yaalon known in Israel for speaking his mind
* U.S. calls his criticism unconstructive and confusing
* Kerry phones Netanyahu to complain (Adds Hagel calls Yaalon over Iran remarks)
By Jeffrey Heller
JERUSALEM, March 20 (Reuters) - Israeli Defence Minister Moshe Yaalon is in hot water again with the United States for caustic criticism of his country's main ally that has put more strain on already testy relations with the Obama administration.
And the hawkish former general, widely popular in Israel for being an apparent straight-shooter who does not shy from speaking bluntly on issues of war and peace, seems reluctant to beat a full retreat from his tough words toward Washington.
Issuing statements voicing regret at any offence he might have caused, Yaalon has not backed away from the substance of a scathing personal attack in January on U.S. Secretary of State John Kerry.
In further criticism on Monday, Yaalon displayed deep disappointment with U.S. President Barack Obama's handling of burning world issues, and he has not retracted his accusation that the world's strongest superpower is projecting weakness abroad.
"Bogie does not take well to being corrected," an ex-adviser, using Yaalon's nickname, told Reuters. Asked what Yaalon might be up to by criticising the United States, he said: "God knows. I hope he does."
In a show of U.S. displeasure, Kerry - derided by Yaalon in January as "messianic" and "obsessive" in his pursuit of Israeli-Palestinian peace - phoned Prime Minister Benjamin Netanyahu on Wednesday to complain about one of the strongest attacks ever by an Israeli defence minister on a top U.S. official.
U.S. Defence Secretary Chuck Hagel, who has good ties with Yaalon, followed up by phoning the minister directly to express "deep concerns" about his comments on U.S. policy toward Iran, the Pentagon said.
Yaalon, in turn, underscored his commitment to bilateral ties, it said.
Netanyahu, whose own relationship with Obama has been fraught with friction over how to deal with Iran's nuclear programme and peace efforts with the Palestinians, has shown little inclination, at least publicly, to rein in Yaalon.
An Israeli official said the 63-year-old Yaalon, who was appointed to his post a year ago, was displaying his inexperience at top-flight government.
"This is his first time in the major leagues and he has now screwed up twice," the official said of Yaalon, a member of Netanyahu's right-wing Likud party and, according to recent opinion polls, the most popular minister in his cabinet.
The official saw no hidden domestic strategy in Yaalon's comments, but thought it was a case of him speaking his mind, when he would have been better served saying nothing.
At a closed-door lecture at Tel Aviv University on Monday, Yaalon, a former armed forces chief, said Israel could not rely on the United States to take the lead in confronting Iran over its nuclear activities.
He also pointed to Ukraine's crisis as an example of Washington "showing weakness".
Yaalon's office later issued a statement saying no criticism or offence was intended towards Washington in his remarks on Monday, although it offered no apology.
"The strategic ties between our countries have a supreme importance, as do our personal ties and mutual interests," it said.
While condemning Yaalon's remarks as unconstructive, inaccurate and confusing, U.S. officials signalled the discord would not have a long-term effect on relations with Israel.
White House spokesman Jay Carney noted "an unshakeable commitment to Israel's security, and State Department spokeswomen Jen Psaki spoke of an "enduring partnership".
Yaalon has a record of breaking ranks over what he perceives as unreasonable risks.
As armed forces chief of staff, his tenure was cut short after he opposed Israel's plan to withdraw settlers and soldiers from the Gaza Strip in 2005.
Some Israeli commentators noted that Yaalon voiced his criticism in private settings - an off-the-record briefing to journalists and the university lecture - and questioned whether he had been naive in thinking his remarks would not be leaked.
A commentary in Israel's best-selling newspaper, Yedioth Ahronoth, openly questioned Yaalon's intelligence.
"Let's call this for what it is: either the defence minister knows something that we don't or, how shall we put this delicately, he is simply a fool," columnist Sima Kadmon wrote.
"That is the only way to explain the behaviour of the most important cabinet minister, whose remarks about the U.S. administration are liable to be catastrophic for the most significant ... relationship that the State of Israel has today." (Additional reporting by Dan Williams; Editing by Mark Heinrich and Sophie Hares)