As a friend from the 1980s, Biden and Israeli Prime Minister had experienced a lot of stress, but the challenge was probably never big as the present.

As a US Vice President, Joe Biden's meetings with Israeli Prime Minister Benjamin Netanyahu often took place in about an hour, with many different emotions, from handshakes or warming to controversy

There are many disagreements that have happened between the US and Israel.

Biden is often considered a "bridge" that helps the two sides have smoothly.

"In that relationship, they can say anything with each other without changing the views on each other," said Dennis Ross, who was a negotiating house and the Middle East advisor of three US Presidential Governments

Francel is something to make a friendship with many years of ups and downs, as well as helping them overcome political chaos both in the country and internationally.

Biden, a loyal ally of Israel during the political career, always supporting the legal self-defense rights of the Jewish national against Hamas rocket attacks, despite criticizing many radical members in the Party

However, the US President had changed his voice with Israel when the casualties in the conflict increased sharply and he spoke calling to end violence.

Netanyahu Prime Minister Netanyahu, who named Bibi, "divided the world into two parts and enemies", according to Ross.

"He can accept criticism and debate. But if it's an enemy, it will never be something like that," Ross said.

Joe Biden, as a US Vice President (left) and Israeli Prime Minister Benjamin Netanyahu in Jerusalem in March 2010.

The relationship between Biden and Israel began nearly half a century ago, when he came to Israel to meet Prime Minister Golda Meir in 1973 as Delaware's Senator.

He was often welcomed in Israel right from the US parliament, especially when held the role of the Senate's Foreign Relations Commission.

The two remained in touch after Netanyahu returned to Israel and eventually became the prime minister in 1996. Their relationship was always maintained even if Netanyahu lost to Ehud Barak in 1999.

Friendship between Biden and Netanyahu began to be challenged when Obama was elected as an American President and Biden was considered to ease all stresses between the two countries.

Netanyahu Prime Minister's office at that time said he did not know before this announcement and denied this as a sign that the lack of respect for America.

Martin Indyk, former US Ambassador and Foreign Relations Council Member, said this experience helped shape Biden's stance to the Middle East peace process under Netanyahu and President Palestine Mahmoud Abbas.

"He concluded that both leaders were unable to make difficulties in capital needed to reach the final peace agreement between Israel and Palestinians," Indyk said.

Some former officials identified Biden - Netanyahu relations with disagreement, sometimes stress.

Another catalyst can cause the relationship between the two people who become stressed to be any proposal about the Arab-Israel peace agreement based on the boundary existing from the six-day war in 1967, as proposed

In the meeting in that year's oval room, Netanyahu warned against the "illusionary peace" and affirmed that Israel would not accept returning to the fifth of the war in 1967, the event helps the country win

"Bibi knows Obama is angry with me, so he thought 'okay, I will negotiate with someone I can negotiate'," Ross said.

When the Obama administration near the nuclear deal with Iran, such privacy discussions became more frank.

Telling that meeting, Biden said he told Netanyahu that "Bibi, I disagree with anything he said, but I love you".

Netanyahu's next year, Netanyahu was invited by Republican members to the US Congress on Iranian Nuclear Agreement and criticized Obama's initiative.

When Biden became an American president, some officials say that the conflict between Israel and the Palestinians is not the administrative priority of the government, instead of pandemic processing and solving its economic consequences

But the return of the Iranian nuclear agreement, reversing the decision to withdraw from the agreement of former President Donald Trump, is Biden's top goal.

"He knows that there will be a battle with Netanyahu about Iranian Nuclear Agreement. He must avoid unreasonable conflicts," Indyk said.