President Obama has bowed his way into controversy yet again.

Pictures of the U.S. president bowing deeply to Japanese Emperor Akihito during a state visit to Japan have incensed some commentators, who say the U.S. head of state should not lower his head before foreign crowned heads. OBAMA-JAPAN/

State Department spokesman Ian Kelly, hit with questions about the bow at a regular news briefing, appeared stumped.

“I saw I’m sure for what it was intended, which is a sign of respect to the emperor. But I don’t have anything from the State Department on it,” Kelly told a news briefing.

Kelly dismissed reports that some critics have gone so far as to call the bow a sign of treason as “a bit extreme,” but said he would check into exactly what sort of protocol briefing the president gets before meeting foreign leaders overseas.

Obama has sparked critical comment with a bow before — there was some harrumphing after Obama lowered his head before Saudi Arabia’s King Abdullah at a G20 meeting in April.