Meseberg, Germany ? President Bush on Wednesday raised the possibility of a military strike to thwart Tehran’s presumed nuclear weapons ambitions.

Bush’s host in two days of meetings at a baroque castle, German Chancellor Angela Merkel, made clear her views on the saber-rattling – however subtle – without directly countering her guest. “I very clearly pin my hopes on diplomatic efforts,” Merkel said, reflecting the deeply held European opinion that military action against Iran is nearly unthinkable.

Merkel joined Bush in urging further sanctions against Iran if it fails to suspend its uranium enrichment program.

Iran’s leader weighed in, too. Speaking before thousands in the central Iranian city of Shahr-e-Kord, President Mahmoud Ahmadinejad said Bush “won’t be able to harm even one centimeter of the sacred land of Iran” and promised continued defiance over Iran’s nuclear activities. Iran says it is enriching uranium to generate electricity, not build a bomb – a claim the West doubts is true.

Bush has alternated lately between slightly more conciliatory and slightly more forceful language on Iran.

Within the coded language of the U.S. attitude toward Iran, several small changes in Bush’s rhetoric Wednesday added up to a difference. Three times, he called a diplomatic solution “my first choice,” implying there are others. He said “we’ll give diplomacy a chance to work,” meaning it might not. He also offered, without even being asked a question about Iran, that “all options are on the table” – a longtime standard refrain, not heard as much lately, that neither confirms nor denies an intention to use military force.

There is no indication the U.S. actually plans any sort of military action, and experts believe it would be an extremely difficult feat tactically for many reasons. Bush’s back-and-forth talk appears designed more to both remind Iran that the U.S. is serious about keeping it from developing a nuclear bomb and to try to finally corral sometimes reluctant allies behind a common firm stand.

Wednesday night, Bush flew from Germany to Rome, where he spends two nights while on a grand farewell tour around Europe.