Barack Obama, the US president, has described the use of chemical weapons in Syria as a "challenge to the world".
I think the chances of a Syrian retaliation against Israel is relatively low. I think President Bashar al-Assad will try to contain the fight because if he takes on Israel as well, it will become engulfed on two fronts ....
And now the US appears to be poised to carry out what Obama has described as "limited, narrow, military strikes" against Syrian targets.
"Young boys and girls gassed to death by their own government. This attack is an assault on human dignity and also presents Syria's danger to our national security. It risks making a mockery of a global prohibition on the use of chemical weapons," said Obama.
"It endangers our friends and our partners along Syria's borders, including Israel, Jordan, Turkey, Lebanon and Iraq. It could lead to escalating use of chemical weapons or their proliferation to terrorist groups who do our people harm. In a world with many dangers, this menace must be confronted."
But Russia's foreign ministry has condemned any possible military action: "Unilateral use of force without UN Security Council authorisation, no matter how limited, is a clear violation of international law, and will undermine prospects for a political and diplomatic resolution of the conflict in Syria."
And Vladimir Putin, the Russian president, said proof must be provided of the use of chemical weapons.
"As for the position of our American colleagues and friends who state that government forces have used weapons of mass destruction - in this case used chemical weapons - and say that they have evidence, let them present it to the UN inspectors and the UN Security Council."
If we are speaking of just symbolic gestures, the consequences will be very very limited actually - except the rising tensions in the whole region. But if ... there's targeting of the Syrian air force capability, this will have a significant impact on the balance of forces within Syria itself. It all depends on the choice of targets.
So, what ramifications could US military action have in Syria and across its volatile borders?
Turkey and Jordan are regarded by Damascus as hostile neighbours and could face repercussions. But it is Israel and Lebanon that are most vulnerable to any fall-out from a US strike against Syria.
The head of Iran's Revolutionary Guard has said a US attack on Syria would lead to the "imminent destruction of Israel".
Israel's defence ministry says the Iranian-backed armed group Hezbollah has up to 70,000 rockets capable of striking Israeli targets.
Any attacks on Israel from Hezbollah could, of course, lead to retaliation against targets inside Lebanon. And sectarian violence in Lebanon, which has increased during the Syrian conflict, could further destabilise the country.
To discuss all of this, Inside Syria, with presenter Hazem Sika, is joined by guests: Meir Javendanfar, an Israeli Middle East analyst and co-author of The Nuclear Sphynx of Tehran; Gilbert Achcar, a professor of International Relations at the School of Oriental and African studies (SOAS), University of London; and Pavel Felgenhauer, a Russian defence analyst who writes for the Novaya Gazeta newspaper.
"The rhetoric in Moscow has been stepped up .... Russia wants to keep the Assad regime. There's a kind of consensus in the Russian expert community and within the military and diplomatic circles, and the Kremlin that a. the majority of Syrians support the Assad regime, and b. that he is fighting an army of outside terrorists, that are al-Qaeda connected and that he's winning this war, and Russia and Iran must support the Assad regime and help him win this war and the regime may be defeated only by a foreign intervention and Russia should do its best to prevent such an intervention. So that's the actual assumption [in Russia] ... of the situation in the Middle East."
Pavel Felgenhauer, a Russian defence analyst