Israel prepping for war with Iran?

Increasing speculation it may be preparing for a military assault on Iran or a regional war involving Hezbollah in Lebanon and Hamas in Gaza, Israel has placed its largest order of military fuel with the United States on record.
The Jewish state, earlier this month, ordered 284 million gallons of JP-8 aviation jet fuel, 100 million gallons of diesel fuel and 60 million gallons of unleaded gasoline – all suitable for military uses – at an estimated cost of $2 billion.
Tensions in the Middle East have escalated since Iran made its nuclear power plant at Bushehr operational with the assistance of Russia earlier this month.
John Bolton, a former U.S. ambassador to the U.N., has warned repeatedly that Bushehr would be much more difficult for Israel to attack after it went operational, largely because any military strike would release radioactivity that could be harmful to the civilian population.
Israel's unwillingness to attack the Iranian nuclear power plant at Bushehr before it went operational has caused considerable controversy within Israel.
Still, many signs point to continuing tensions in the Middle East that could easily escalate into war.
Olli Heinonen, the former head of U.N. nuclear inspections worldwide, claimed this week that Iran has stockpiled enough low-enriched uranium to make one to two nuclear bombs. 
Nevertheless, the White House cautions that Iran is not on the verge of developing a nuclear weapon.
Why does the Obama White House insist that there is no threat from Iran?