The top adviser of Israeli Prime Minister Benjamin Netanyahu said Sunday that differences might be emerging during the meeting between Netanyahu and US President Barack Obama in Washington on Monday.

"Clearly there could be some differences of opinion between the sides in respect to two states for two peoples." National Security Advisor Uzi Arad was quoted by the website of local daily Jerusalem Post as saying.

"There are many hurdles" on the road to living side by side in peace with the Palestinians, he said, citing the takeover of the Gaza Strip by Hamas in June 2007.

"That is the presence of a huge terrorist infrastructure that was put in place, established precisely at the time when Israel evacuated Gaza and allowed the Palestinians to rule themselves," said Arad, shortly after Netanyahu arrived Sunday in Washington.

Netanyahu is expected to propose to Obama that joint teams draft a new road map for the Palestinian peace process and a new strategy on Iran.

Arad said that he hoped Netanyahu's talk with Obama would focus on the Iranian nuclear issue.

"This is not only an existential issue for the State of Israel, but also a very worrisome one because Iran is constantly progressing on this front," he added.

"There is a sense of urgency on our side" and the prime minister will be "emphatic in emphasizing that sense of urgency," he was quoted as saying.

In an interview published ahead of his meeting with Netanyahu, Obama reiterated comments made by other top officials, saying that he understands why Israel considers Iran as an existential threat.

"I understand very clearly that Israel considers Iran an existential threat, and given some of the statements that have been made by (Iranian) President (Mahmoud) Ahmadinejad, you can understand why," Obama said in an interview with Newsweek, which was published on its website.

(Xinhua News Agency May 18, 2009)