The US military’s top general said late Sunday that Israel and the US see the Iranian threat differently, admitting that Washington and Jerusalem are on “different clocks” regarding Tehran’s nuclear ambitions.

Gen. Martin Dempsey, head of the US Joint Chiefs of Staff, told reporters while on a flight to Afghanistan that he understood Israel’s urgency in calling for action against Iran’s nuclear program.

“They are living with an existential concern that we are not living with,” he said, according to AFP.

Dempsey reiterated his estimation that Israel could delay but not destroy Iran’s nuclear program. But he said he did not know the details of any Israeli military plan; the US and Israel were allies, he said, but did not share everything.

Dempsey added that he and Israel Defense Forces Chief of General Staff Benny Gantz spoke on a bi-weekly basis to coordinate intelligence, despite gaps in understanding how close Iran is to the point of no return.

“We compare intelligence, we discuss regional implications. And we’ve admitted to each other that our clocks are turning at different rates,” he said.

Dempsey’s statement comes as chatter has ramped up over a possible Israeli strike on Iran’s nuclear program. The US is reportedly working to keep Israel from launching a unilateral strike, saying that sanctions should be given more time to work.

Israeli officials have spoken before of differing with Washington over where “red lines” existed with advances in Iran’s nuclear program.

Defense Minister Ehud Barak reportedly believes Iran is only a few months away from crossing the threshold beyond which a military strike on their program will be useless, while the US believes it has more time.

Both Barak and Netanyahu reportedly prefer for the US to lead in any such strike, but say they will go it alone if they have to.

Dempsey reiterated his view that an Israeli strike would only set Tehran back by about a year.

Israeli officials have pointed to a 1981 strike on Iraq’s Osirak nuclear facility, which knocked Baghdad out of the nuclear arms race despite analysts’ views that it would only be marginally effective, as an argument for going it alone.