Prime Minster Binyamin Netanyahu on Tuesday addressed raised concerns that Syrian President Bashsar Assad could be preparing to use chemical weapons in his fight to survive against opposition forces, stating that Israel was monitoring the situation closely.Israel has said on several occasions in the past that it would take military action if necessary to prevent Syria's stockpile of chemical weapons from falling into the hands of Hezbollah or other terror groups.After US President Barack Obama and NATO Secretary-General Anders Fogh Rasmussen warned Assad against using chemical weapons on Monday and Tuesday respectively, Netanyahu said Tuesday, "We are monitoring closely, along with the international community, the events in Syria with regard to the chemical weapons stockpiles."Netanyahu said that he "heard the important statement made by President Obama on this matter and I agree, these weapons cannot be used or transferred to terrorist organizations. "The head of NATO, asked about possible use of chemical weapons by the Syrian government, said on Tuesday that any such act would provoke an immediate international response."The possible use of chemical weapons would be completely unacceptable for the whole international community," NATO Secretary-General Anders Fogh Rasmussen told reporters."If anybody resorts to these terrible weapons, then I would expect an immediate reaction from the international community," he said.Rasmussen's statement followed a similar warning by Obama to Assad on Monday not to use chemical weapons against Syrian opposition forces, saying there would be consequences if he were to do so."I want to make it absolutely clear to Assad and those under his command: The world is watching," Obama said in a speech to a gathering of biological, chemical and nuclear weapons proliferation experts."The use of chemical weapons is and would be totally unacceptable and if you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable," Obama said.He did not say how the United States might respond, but White House spokesman Jay Carney said earlier that "contingency planning" was under way when asked whether the use of military force was an option.It was unclear what has motivated US officials to think that Syria might be on the verge of using chemical weapons.An American official said the United States is concerned that Syria may be preparing to combine the chemicals needed to make sarin gas.As Assad's government has shown signs of increasing strain in response to recent advances made by the rebels, Carney said the United States has grown concerned that the Syrian president might be considering the use of chemical weapons.This would, Carney said, "cross a red line for the United States."The Atlantic reported Monday that Israel asked Jordan on a number of occasions for "permission" to bomb Syrian chemical weapons sites, citing intelligence sources in both countries.According to the report, Jordan turned down requests a number of times in the past two months, saying "the time was not right." Jordan is reportedly wary of allowing Israel to bomb the sites in Syria, fearing a military response on Jordanian territory. "A number of sites are not far from the border," the report quoted a foreign source as saying.