Israel delivers strongly worded message to U.S., following comments advising Israel not to attack Iran’s nuclear facilities • Defense Minister Ehud Barak: We are responsible for our own decisions concerning our future.

Israel on Monday demanded that the U.S. challenge Iran to immediately put an end to its nuclear program while the U.S., for its part, urged Israel to allow sanctions against Iran to do the job and cease planning for a military strike.

The exchange occurred in a meeting between U.S. National Security Adviser Tom Donilon and Defense Minister Ehud Barak and Chief of General Staff Lt. Gen. Benny Gantz, one of several that U.S. government officials have recently held with their Israeli counterparts in ongoing discussions concerning the Iranian issue. On his visit to Israel this week, Donilon also met with Prime Minister Benjamin Netanyahu, who is scheduled to travel to Washington next month where he will meet U.S. President Barack Obama on March 5, according to a White House statement.

Israeli officials clarified that as long as Iran does not halt its nuclear program entirely, action must be taken now to stop it from progressing any further. “The conversation covered a broad spectrum of topics that relate to our ties as well as a variety of issues concerning the entire region,” Barak said after his meeting with Donilon. Barak pointed out that Israel’s ties with the U.S. involve those of “sovereign countries that are ultimately responsible for their own decisions and futures.”

Israeli government officials believe Iran is using diversionary tactics - such as agreeing to talks with Western countries - to stall for time and allow it to advance its nuclear program. The U.S. position is that there is still time for options - other than military action - to run their course.

Meanwhile, Iran continues flouting the international community’s request for greater transparency about its nuclear program and continues to play war games. As U.N. nuclear inspectors arrived in Iran on Sunday for talks with Iranian officials about how far the country’s controversial nuclear program has advanced, Iran’s army began a drill to test the defenses of its nuclear facilities against an aerial assault. The four-day exercise - code-named “God’s revenge” - is said to be testing advanced anti-aircraft missile systems, as well as artillery, radar, and management and control systems.

As International Atomic Energy Agency officials met with Iranian officials, Iran announced that in the coming months it intended to replace the core of a reactor in one of its nuclear facilities near Tehran with a more advanced version. In the same statement, the Iranian government spokesperson said that Iran continues to make important strides in its nuclear capability.

A spokesman for Iran’s Foreign Ministry on Tuesday said the visiting U.N. team has no plans to inspect the country’s nuclear facilities but will only hold talks with officials in Tehran. On Monday, Iranian radio said the U.N. team had asked to visit a military complex outside Tehran that has been suspected as a secret weapons-making location.

Ramin Mehmanparast said the IAEA experts are holding discussions Tuesday in Tehran to “accelerate” cooperation with the U.N. watchdog. He says this cooperation is at its “best” level. The two-day IAEA visit, which started Monday, is the second in less than a month by the U.N. team amid growing concerns over alleged Iranian weapons experiments .

Iran also said it would take pre-emptive action against its enemies if it felt its national interests were endangered, the deputy head of the Islamic Republic’s armed forces was quoted by a semi-official news agency as saying on Tuesday.

“Our strategy now is that if we feel our enemies want to endanger Iran’s national interests, and want to decide to do that, we will act without waiting for their actions,” Mohammad Hejazi told Fars news agency.

Following Iran’s announcement on Sunday that it was halting shipments of crude oil to Britain and France, Iran’s Oil Minister Rostam Qassemi said on Monday that the country would halt oil shipments to other European countries if they moved forward with sanctions against Iran. The European Union imposed an embargo on oil imports from Iran, to start from July 1.

Qassemi warned the price of crude oil could reach $150 per barrel. On Monday, the price-per-barrel reached a nine-month high of more than $103.

Meanwhile, the Yomiuri newspaper in Japan, citing unidentified sources, said Japan and the U.S. reached an agreement at talks last week about the size of cuts to crude imports from Iran, with a formal deal expected by the end of this month.

Avoiding sanctions is essential to protect the Japanese financial sector’s operations abroad, but cutting oil imports could pose a risk to Japan’s economy. Reliance on oil imports has grown since a 2011 earthquake and tsunami triggered the Fukushima radiation crisis, leading to most nuclear reactors at Japanese power plants being shut down.

“We are closely negotiating with the United States and are moving forward toward mutual understanding, but it is not the case that we have reached a conclusion,” Trade Minister Yukio Edano told reporters.

Iran, the biggest oil producer in OPEC after Saudi Arabia, denies Western suspicions that its nuclear program has military goals, saying it is for purely peaceful purposes.

At the same time that the U.S. government focuses on diplomatic efforts and sanctions, it is also trying to persuade Israel not to launch an attack on Iran’s nuclear facilities. The New York Times reported on Monday that Israel would not be able to successfully strike Iran on its own, saying that “its pilots would have to fly more than 1,000 miles across unfriendly airspace, refuel in the air en route, fight off Iran’s air defenses, attack multiple underground sites simultaneously - and use at least 100 planes.”

According to The New York Times, that assessment is supported by a large part of the U.S. military establishment, many of whom point out that a strike on nuclear facilities in Iran would require much more than the surgical strike Israel carried out against Iraq’s Osirak reactor in 1981 and the 2007 attack on a nuclear reactor in Syria that foreign media have attributed to Israel.

The report explained the practical difficulties involved in such a strike, and said there are “three potential routes [to reach Iran]: to the north over Turkey, to the south over Saudi Arabia or taking a central route across Jordan and Iraq.” It added that military experts say the third choice - over Jordan and Iraq - would be the best path, since Iraq has had no air defense systems in place since U.S. forces left the country last year.

The next problem, says the article, is distance. Although the Israel Air Force possesses F-15i and F-16i combat aircraft, they will not be able to fly to Iran without undertaking complicated refueling operations in midair, and it is not certain that Israel has enough airborne refueling planes (tankers) to fulfill that task. Even if they do have enough tankers, the Times reported, additional combat aircraft would be required for protection during refueling.

Aside from Iranian anti-aircraft systems, The New York Times article cites other obstacles to an aerial strike on Iran, such as the fortified bunkers that house some of its nuclear facilities. Although Israel does reportedly have U.S. manufactured “bunker buster” bombs, it is unclear how far underground they can penetrate.