The U.S. has been formulating its response to an alleged chemical attack carried out by Syrian forces that killed hundreds of civilians last month. "These are crimes against humanity and they cannot be tolerated," Kerry warned.
In a deal meant to avert a threatened U.S. military strike, U.S. and Russian officials reached an ambitious agreement over the weekend calling for an inventory of Syria's chemical weapons program within one week. All components of Syria's chemical weapons program are to be removed from the country or destroyed by mid-2014. The Syrian government has yet to issue an official statement on the agreement.
The deal was greeted with cautious optimism in Israel, where leaders expressed satisfaction that Syria, a bitter enemy, could be stripped of dangerous weapons but also pessimism about whether Syrian President Bashar Assad will comply.
Israel has repeatedly voiced concern that Assad, locked in a two-year-old civil war, may fire his chemical weapons at Israel in a bout of desperation or that the weapons could fall into the hands of Hezbollah or other hostile groups fighting in the Syrian civil war.
Perhaps more critically, the Israelis also fear that a tepid international response to Syria could encourage Iran to press forward with what is widely believed to be a nuclear weapons program. Iran denies its nuclear program has a military purpose and says it is pursuing peaceful applications like cancer treatment and power generation.
Standing alongside Kerry, Prime Minister Benjamin Netanyahu welcomed the U.S.-Russia deal and stressed his belief that it would have deep repercussions on Iran, Syria's close ally.
"The world needs to ensure that radical regimes don't have weapons of mass destruction because as we have learned in Syria if rogue regimes have weapons of mass destruction they will use them," Netanyahu said.
"The determination the international community shows regarding Syria will have a direct impact on the Syrian regime's patron Iran. Iran must understand the consequences of its continued defiance of the international community by its pursuit toward nuclear weapons," he added.
He said the deal proved that "if diplomacy has any chance to work, it must be coupled with a credible military threat."
With a nod toward these Israeli concerns, Kerry stressed that the deal with Russia was merely a "framework," and much would depend on Syria.
"The threat of force is real and the Assad regime and all those taking part need to understand that President Obama and the United States are committed to achieve this goal," Kerry said.
He also said the agreement, if successful, "will have set a marker for the standard of behavior with respect to Iran and with respect North Korea and any rogue state, (or) group that tries to reach for these kind of weapons."
Ahead of Kerry's arrival, some Israeli politicians voiced skepticism, saying Assad cannot be trusted.
Intelligence Minister Yuval Steinitz said the plan was more "substantive" than earlier proposals, but warned the agreement's deadline was not speedy enough and Assad could try to hide weapons.
"We know Assad. All kinds of things could happen," he said, adding that an agreement on chemical weapons should not absolve Assad of punishment for the acts he has committed against the Syrian people.
Avigdor Lieberman, chair of parliament's foreign affairs and defense committee, told Army Radio that Israel would compare its own intelligence assessments of Syria's weapons to the inventory Syria submits, which the plan requires him to do in a week.
"After we see the list of what Assad has handed over in a week, we can know if his intentions are serious of if it is just deception," Lieberman said.
After their news conference, Kerry departed for Paris where he was to discuss the Syria plan with his French, British, Turkish and Saudi counterparts on Monday.