I'm not a big believer in conspiracies, but on the other hand, I'm not much of a believer in coincidences, either. So I'm having trouble understanding why the FBI announced last week it had arrested an Israeli spy more than 20 years after his alleged espionage occurred and about 20 days before President Bush is scheduled to be in Jerusalem to celebrate Israel's 60th birthday. Conspiracy gourmands on all sides are feasting on this one. The first name to pop up, as usual, was that of Jonathan Pollard, imprisoned since he was caught in 1985 with a treasure trove of purloined papers stolen while he was a U.S. Navy intelligence analyst. His backers, ever sensitive to new conspiracies about their hero, say the arrest of Ben-Ami Kadish, a retired civilian engineer for the U.S. Army, was a plot to prevent an anticipated presidential pardon for Pollard, possibly as a birthday gift for Israel. On the other hand, one military analyst who has followed his case closely, speculated that Pollard may have given up Kadish - they apparently both had the same control officer - in a bid to buy his freedom by showing he was finally giving in to US government demands that he come clean about who else was working with him. There is no evidence to support either theory, but that hasn't slowed the speculation. Kadish, whose access and security clearances were inferior to Pollard's, could not have been the high-level US government mole - dubbed Mr. X - some prosecutors suspect was pointing Pollard to the most important secrets. The arrest of the 84-year-old American-born engineer came just a few days before White House visits by the King of Jordan and the Palestinian Authority President Mahmoud Abbas, both of whom appealed to the President to increase pressure on Israel if he hopes to realize his goal of a peace agreement before leaving office in January. And it was shortly before the trial of two former staffers of the American Israel Public Affairs Committee accused of passing secrets to Israel. THE BIG questions being asked in Jerusalem and Washington are why now and what impact this new spy case will have on the overall US-Israel relationship. The Jewish right warns it is part of a squeeze on Israel to bow to pressure on a deal with the Palestinians and to bolster prosecutors in the AIPAC case. Military analyst and author Norman Polmar says whatever the government's motive in acting now, the case is an "I told you so" for what he calls the informal anti-Israel lobby in the defense, intelligence and security establishment. "People who don't like the close US relationship with Israel will get a lot of ammunition out of this; the next time the Israelis ask for a new weapon, access to new technology or to initiate a joint intel project, they'll say we can't do this, they can't be trusted, just look at the Kadish and Pollard cases," he said. "They'll argue the special relationship does the US more harm than good." Even friends of Israel will be asking questions, he added. "That won't stop cooperation, but it could slow it down while people examine requests more closely and opponents raise more objections." Another piece of lingering fallout from the Pollard case, another analyst said, is more frequent and tougher reviews for Jews who have security clearances. "This case didn't come out of the blue," said a military expert with close ties to both the American and Israeli defense establishment. "What were they (US officials) doing that they just stumbled over this?" Kadish's arrest highlights the fact Pollard's case was not unique, as claimed, and is reviving questions about how many other American Jewish spies Israel had. It also points to the fact that Israel has never come clean with US officials about its 1980s spying. BUT WHO's spying on whom? Kadish apparently ended his espionage career before Pollard was arrested in late 1985; at that time Israel's top three leaders - Yitzhak Rabin, Yitzhak Shamir and Shimon Peres - ordered a halt to all covert operations in the US. But even if Israel did stop spying on the US, the US has not stopped spying on Israel and is very likely monitoring all forms of communication, still looking for Mr. X. We do know that they were listening in when Kadish and his former handler in Israel spoke by phone on March 20. The Pollard case continues to cast a giant shadow over U.S.-Israel relations, and it doesn't help that his apologists insist his actions were justified because he felt the US was not telling and giving its ally Israel all it needed. The greatest damage of the Kadish case may come from a tiny minority in the Jewish community that seems to justify spying by claiming Washington has not supported Israel with intelligence about its enemies and with political backing. And they make things worse when they belittle the latest case by ridiculing it as government harassment of an elderly "zayde." Such conduct can be as destructive as the crime itself; it says that spying for Israel is not only acceptable but honorable and even necessary - and it reinforces accusations that Jews put loyalty to Israel ahead of loyalty to America.