German Chancellor Angela Merkel and U.S. President Donald Trump aired differences over trade and NATO on Friday at a White House meeting where they tried to put on a show of warmth and friendship despite tensions between the two allies.

With Trump poised to impose tariffs on steel and aluminum soon that will impact European exports, Merkel said the decision is now in Trump's hands on whether to grant exemptions to European Union nations.

"We had an exchange of views. The decision lies with the president," Merkel told a joint news conference after Trump complained about the U.S.-European trade imbalance, particularly in regards to automobiles.