Michael Barone‘s latest column examines the president’s propensity for angering American allies.

Obama’s best moments in foreign policy have been when he has followed the lead of his predecessors. For instance, in his twice-postponed trip to Australia this week, he will reportedly announce that a U.S. Navy base will be opened there.

That will cement ties already strengthened by George W. Bush and previous presidents to the one nation in the world that has fought alongside the United States in every war in the last century.

But domestic politics can trump foreign policy for Obama: He cancelled previous Australian trips to lobby the House to pass Obamacare and to respond to the Gulf oil spill.

Closer to home, crassly political ploys have angered the governments and people of our two geographical neighbors, Mexico and Canada.

Only domestic politics can explain two of the Obama administration’s most controversial moves: exporting illegal guns to Mexico and balking at allowing an oil pipeline from Canada.