Vice Prime Minister Shaul Mofaz meets U.S. President Barack Obama and thanks him for standing by Israel • Mofaz: Iran must understand that if Israel feels its existence is threatened, it will act alone if necessary.

Vice Prime Minister and Kadima Chairman Shaul Mofaz met U.S. National Security Advisor Tom Donilon in the White House on Thursday and during their conversation, President Barack Obama entered the room and spoke with Mofaz for half an hour.

Obama has adopted the protocol of "dropping in" on a guest that is not a head of state as a way of showing respect for the senior government official. Israeli officials saw the act as the U.S. president´s way of expressing support for Prime Minister Benjamin Netanyahu´s decision to bring Kadima into the government.

Israeli Ambassador to the U.S. Michael Oren, was also present at the meetings.

Mofaz thanked Obama for standing by Israel and its security needs. A statement from his office said "The discussion went very well."

In his discussion with Obama, Mofaz said that the failure of three rounds of negotiations with Iran concerning its nuclear program means that the next set of tougher sanctions should include an embargo on Iran´s crude oil exports. However, if all other efforts fail, he said, including more severe sanctions, the U.S. must lead a military strike on Iran.

Six world powers and Iran failed to secure a breakthrough at talks in Moscow this week, the third round under the latest diplomatic initiative, and set no date for more political negotiations.

Technical talks with Iran have been scheduled for July 3 in Istanbul, but no further political talks have been agreed to, and some experts have said the risk of war will increase unless diplomacy is renewed.

On Wednesday, after a discussion with U.S. Secretary of State Hillary Clinton, Mofaz released a statement that said "It is time for the United States and Western powers to impose more severe sanctions in the oil embargo and financial sectors in order to stop Iran´s nuclear development program."

Speaking with the U.S. president, Mofaz sent a warning message to Iran, saying that if Israel feels its existence is threatened, it will be able to carry out a military operation against the Islamic republic on its own.

On his four-day visit to the U.S. capital, Mofaz is also seeking U.S. help in arranging a meeting with Palestinian Authority President Mahmoud Abbas to try to renew peace talks deadlocked since 2010.

Concerning talks with the Palestinians, Mofaz told Obama there is no date for the renewal of negotiations and no outline for such talks, but there is a willingness to move forward and he plans to meet with Abbas in the near future.