Israeli warplanes mounted an attack on a Syrian military base this week, according to an American official cited by US media.
There may be a ceasefire on the surface at the Gaza border, but for the Israeli army the threats can come from underground.
Israel has admitted it fired two missiles in the Mediterranean. It initially denied any knowledge of missiles being fired.
US Secretary of State John Kerry has sought offer assurances to Israel over the Iran nuclear deal, saying that the agreement would make Israel safer over the next six months.
Kerry told CNN's State of the Union: "Israel is threatened by what has been going on in Iran.
"But I believe that from this day - for the next six months - Israel is in fact safer than it was yesterday, because we now have a mechanism by which we are going to expand the amount of time in which they [Iran] can break out [toward creating a nuclear bomb].
"We are going to have insights to their program that we didn't have before".
Israel's Prime Minister Benjamin Netanyahu has called the nuclear deal with Iran "an historic mistake" and said it has "made the world a much more dangerous place".
He said that the international community appeared to have switched position in not calling for a complete end to all uranium enrichment, and accused Iran of taking "cosmetic steps which it could reverse easily within a few weeks".
"Without continued pressure [on Iran], what incentive does the regime have to take serious steps which actually dismantle its nuclear weapons capability?"
"Israel is not bound by this agreement," he added.
Israel's Prime Minister Benjamin Netanyahu has described the deal on Iran's nuclear programme as an "historic mistake".
President Barack Obama plans to talk to the Israeli prime minister later today about Netanyahu's concerns, a senior US official said.
US Secretary of State John Kerry will visit Geneva to join nuclear negotiations with Iran and other major powers, the Associated Press reported, citing official sources.
Kerry's last-minute decision to join the talks suggests a deal could be imminent.
He will participate in the talks after a brief stop in Israel, where he will hold a third meeting with Israeli Prime Minister Benjamin Netanyahu.
The Israeli government has denied any role in the death of Yasser Arafat, saying that he was 75-years-old.
"This is more soap opera than science, it is the latest episode in the soap in which Suha opposes Arafat's successors," Israeli Foreign Ministry spokesman Yigal Palmor said.
The investigation amounted to "a highly superficial attempt to determine a cause of death".
Israel said it would not allow advanced weapons to fall into the hands of Hezbollah, after reports it had attacked a Syrian air base holding missiles for the militant group.
Israel declined to comment on media reports that its planes had hit the base near the port of Latakia.
However, Home Front Defence Minister Gilad Erdan told Israeli radio: "We have said many times that we will not allow the transfer of advanced weapons to Hezbollah. We are sticking to this policy and I say so without denying or confirming this report."
A quite extraordinary situation has developed in the Middle East, where Israel can carry out airstrikes on what used to be a great power, Syria, and it can do so with impunity.
Israel has made no comment on the air strike, which reportedly targeted a missile delivery, but then it never does. Six times now, by my count so far this year, Israel has carried out air strikes inside Syria.
They're all on similar targets, sophisticated weapons such as surface-to-air missiles made in Russia, that Israel thinks are in the process of being delivered to the Assad regime's great ally, the Lebanon-based militia group Hizbollah.
There has also been no comment from the Assad regime on this air strike, certainly no kind of military response. The Assad regime of course has its hands full fighting the civil war.
Israeli fighters which struck a Syrian airbase near the port of Latakia were targeting missiles that were thought to be on their way to Lebanese militia group Hezbollah, said Reuters citing an an unidentified US administration official who spoke to CNN.
The airstrike on Thursday was the latest of several carried out by Israel this year, which has said it will act to defend its territory if needed. Israel does not comment on its military operations.
The attack involved two to four aircraft, said USA Today citing a security official speaking to AP.
Israeli warplanes mounted a new attack on a Syrian military base on Thursday, according to a US official cited by the Associated Press.
The strike hit the Syrian port city of Latakia and the target was Russian-made SA-125 missiles, according to the anonymous security official.