The United States and Israel are cooperating very closely on all issues, including the developing matters in Syria, Prime Minister Binyamin Netanyahu said Monday in a meeting with US congressmen visiting Israel. "I think this is very important for stability in the region," the prime minister added, emphasizing his appreciation to the United States.Such a development would be "a crossing of all red lines that would require a different approach, including even preventive operations," he said - alluding to military intervention, for which Israeli generals have said plans have been readied."The concept, in principle, is that this (chemical weapons transfer) must not happen," Shalom said. "The moment we begin to understand that such a thing is liable to happen, we will have to make decisions."Netanyahu's comments came as National Security Council head Yaakov Amidror traveled to Russia to discuss the Syrian crisis, Army Radio reported.According to the report, Amidror plans to discuss the issue of Syrian chemical weapons with officials in the country.The fighting and instability in Syria and the uncertainty over the security of Syria's chemical weapons arsenal has been a cause of ongoing concern for Israel's decision makers. Strategic Affairs Minister and Vice Premier, Moshe Ya'alon, speaking to Army Radio on the prospect of the leaking of chemical weapons from the Syrian army to terrorist groups such as Hezbollah said: "The situation in unstable and is becoming less stable from day to day. The worry stems from the fact that Syria possesses chemical weapons. We can wake up in the morning and see that everything has changed there." Ya'alon denied that Israel intends to intervene militarily in Syria. "As long as Israel is not threatened, we will not intervene in Syria," he said.Any sign of Syria's grip on its suspected chemical weapons slipping as it battles an armed uprising could trigger Israeli military strikes, Israel's vice premier, Silvan Shalom, said on Sunday.Shalom confirmed a media report that Netanyahu had last week convened security chiefs to discuss the civil war in nearby Syria and the state of the country's chemical arsenal.The meeting, held on Wednesday, had not been publicly announced and was seen as especially unusual as it came while votes were still being counted from Israel's national election the day before, which Netanyahu's party list won narrowly.Should Lebanon's Hezbollah guerrillas or rebels battling forces loyal to Syrian President Bashar Assad obtain Syrian chemical weapons, Shalom told Israel's Army Radio, "it would dramatically change the capabilities of those organizations."