This is meant to be the first of two or three posts discussing the way that anti-Semitic rhetoric functions in today’s political discourse, using Mark Glenn’s disgusting piece of Jew-hatred, published by the Palestinian Authority (your development assistance dollars at work) as a starting point. The introduction can be found here.
It is hardly a new observation that critics of Israel sometimes step over the line into open anti-Semitism. Or even that anti-Semites have been consciously and intentionally clothing some of their Jew-hatred in the sheep’s wool of anti-Zionism (for the purposes of this discussion, I'll bracket the question of whether the Left's rabid anti-Zionism - picking out Jews as the only ethnicity on the planet to not have a right to self-determination - is inherently anti-Semitic).
The strategy is to smuggle in anti-Semitic rhetoric as legitimate in polite politial discourse by tangling it up with anti-Israel rhetoric. Anti-Semites can get away with alot by making a claim about Jews but by changing the word "Jew" to "Zionist."

The point is obvious: The word Zionist doesn't really fit there. He meant Jew, and moreso it's obvious he meant Jew. But herein lies the trick - if Glenn were to be accused of anti-Semitism for this line, he would cry foul, insisting that he was being accused of anti-Semitism simply because he was criticizing Zionism or the State of Israel.
The scandal about Amiri Baraka is an excellent illustration of this strategy. Baraka, you'll remember, was the New Jersey Poet Laureate who took the myth that was at the time running rampant through Arab newspapers - that there were no Jews in the World Trade Center on 9/11 - changed the word "Jews" to "Israeli," and put a line about how Israel told all the Israelis to get out of the World Trade Center in a poem (rebound to West Wing: "when you vet your nominees, do you go so far as to actually talk to them?"). He later presented this as proof that Israel knew about the bombing: an Israeli firm "must have had Mossad input because they vacated one week before September." "Must." Clearly. And of course, when accused of anti-Semitism, he argued that he was being targeted because of anti-Israel political ideology and angrily insisted that "criticizing Israel does not mean you're anti-Semitic." And don't think that he was the only one who managed to spin his anti-Semitism as anti-Zionism simply because he used a word that everyone understood to be but was not literally "Jew" - Pravda's headline was "State Poet Asked to Resign for Criticizing Israel."
The answer to this is not simple - of course people can criticize Israel and not be anti-Semitic. But that doesn’t mean that someone can’t be anti-Semitic while criticizing Israel. To put it another way, some people who criticize Israel and are accused of anti-Semitism are innocent, but that doesn't mean that anyone accused of anti-Semitism is innocent because they're criticizing Israel. When something clearly doesn’t fit (like claiming that 4,000 “Israelis” didn’t show up to work at the WTC, when the popular myth talks about 4,000 “Jews”), it can reasonably be called out for anti-Semitism.
There is an even more subtle way of smuggling in anti-Semitism in the guise of anti-Israel arguments. Instead of tangling the two together in the same statement, which leaves the possibility of untangling them, anti-Semites will make criticisms of Israel that play upon anti-Semitic canards.
Take, for example, the oft-sited complaint that Israel sucks the US economy dry by taking the money of Americans. This is on it's face an anti-Israel argument. But it also does persuasive work by evoking an anti-Semitic trope. There is more going on in that statement than just a straight-forward criticism of Israel. Ditto for arguments about shadowy Jewish cabals that have hijacked the US government.
What’s going on under the surface is that the anti-Semitic tropes that are being invoked are doing rhetorical and persuasive work for the author. The theme of greedy Jews works to sustain what the author is trying to accomplish. These rhetorical moves thus need to be called out in the same way that we would call out more open anti-Semitism - the purpose is the same, and the effects are the same.