I'm not the kind of person that thinks that only the lives of Americans matter. Of course they do matter, but so do the lives of people with different nationalities.
But for U.S. politicians it's not like that. We know exactly how many Americans are killed in any conflict. The body counts of the Vietnamese or Iraqis are much less well known.
But let's play this game of pretending only the lives of Americans matter. Here's something that makes Americans unsafe. U.S. support for Israel. Support for the interests of Israel costs American lives. Look at the #1 reason OBL gave for his attacks against the United States. It is attacks from Israel on Muslims done with U.S. support.
Today Netenyahu is moving forward with plans to build additional settlements in occupied Palestinian territory. This is the equivalent of Mexico crossing in to Texas and building homes for Mexicans subject to Mexican laws, all the while displacing native Texans. Obviously this is not how you go about making peace with your neighbors.
How does this affect the safety of Americans? General David Patreaus told Congress that this flares large scale conflicts, foments anti-American sentiment, limits the strength of partnerships between the U.S. and Arab governments, strengthens Al Qaeda, and improves Iranian influence in the region. All of these consequences quite naturally put U.S. troops in danger and cost American lives.
The fact is Israel's interests do not necessarily coincide with American interests. An attack on Iran would be dangerous for Americans, though the Israeli government indicates a desire to move forward with that. Many American politicians and pundits support that. It's worth noting the politicians that put the interests of a foreign nation ahead of the safety of American troops and citizens.