The US must take action in Syria to send a message that Syrian leader Bashar Assad’s use of chemical weapons cannot be tolerated, Labor leadership candidate Isaac Herzog said Monday.Herzog has built close ties with figures in the Syrian opposition over the past two years. He said he warned correctly at the start of the Syrian civil war that if the international community failed to intervene militarily, the situation in the war-torn country would deteriorate significantly.“The rogue states have to be told that there are lines that cannot be crossed,” Herzog said.Crisis in Syria - full JPost.com coverageNeither Herzog, nor his competition in the Labor race, opposition leader Shelly Yacimovich, would address reports that Prime Minister Binyamin Netanyahu had been enlisted by Obama to draft support in Congress for a strike on Syria.“Due to the sensitivity and complexity of the situation, she will not publicly address the issue [of Netanyahu’s involvement],” a spokeswoman for Yacimovich said. “The blabber on this issue should be kept to a minimum.”Speaking more generally on Syria, Yacimovich said: “The world cannot remain indifferent and stand aside when a leader slaughters his people with gas, which is a crime against humanity. The friendship and the bond with the US is a top strategic asset for us. We must appreciate the US taking upon itself the ethical leadership of the international community on this issue.”“The Middle East sees the US as the leader of the free world, so the message of President Obama is reverberating loud and clear. He’s taking the lead and trying to get clear support, though he has been limited by Russian and Chinese vetos.”Herzog stopped short of criticizing Obama for not attacking Syria already. He said Israel needed to take a back-seat role and continue cooperating with the US, as adverse developments continue in Syria.“I can understand the president’s need to get support from Congress, but as an Israeli leader, there are moments when you don’t have any choice,” he said. “If the rogue states see that nothing will happen after Assad slaughters his own people with chemical weapons, the message will be that there is no world order.”Herzog said he disagrees with those who believe an attack on Assad would help al-Qaida.He said he believes the Syrian opposition would democratically choose leadership that would be secular and could bring stability.