WASHINGTON -- Susan Rice, US President Barack Obama's national security advisor, said on Tuesday night that Prime Minister Benjamin Netanyahu's acceptance of an invitation to address Congress next month is "destructive of the fabric of the relationship" between Israel and the United States."We've been fortunate that politics have not been injected into that relationship," Rice said to American journalist Charlie Rose. But "what has happened over the last several weeks, by virtue of the invitation that was issued by the Speaker and the acceptance of it by Prime Minister Netanyahu on two weeks in advance of his election, is that on both sides, there has now been injected a degree of partisanship."Those decisions from both men were "not only unfortunate," Rice continued, but "destructive.""It's always been bipartisan," she said. "We need to keep it that way. We want it that way. I think Israel wants it that way. The American people want it that way. And when it becomes injected or infused with politics, that's a problem."Netanyahu accepted the invitation in late January, originally scheduling him to speak in mid-February. He requested the speech be delayed until March 3, when he will already be in Washington for the annual conference of the American Israel Public Affairs Committee.Both of his speeches, to AIPAC and to Congress, are expected to focus on a pending international deal on Iran's nuclear program, which he vehemently disapproves of. In a letter to Senate Democrats on Wednesday, Netanyahu said he planned to "voice Israel's grave concerns about a potential nuclear agreement with Iran that could threaten the survival of my country."Negotiators from Iran, the US, United Kingdom, France, Russia, China and Germany seek to clinch a political framework agreement on the nuclear issue by the end of March.As first reported in The Jerusalem Post in November, US officials are suggesting a deal with a sunset clause in roughly ten years, during which Iran would gradually be granted the rights and privileges of fellow signatories of the Nuclear Non-Proliferation Treaty.All five permanent members of the United Nations Security Council, Arab powers and Israel believe Iran has been in violation of its international obligations under the NPT, growing its nuclear program in size and scope while experimenting with weaponization techniques."They're not going to be able to convince anybody on day one that they have stopped enrichment," Rice said to Rose, speaking of a possible deal."They're going to have to prove over time through their actions which will be validated that they are, in fact, upholding their commitments. So this will be a phased process any way you slice it."