Trump 'unwavering' in commitment to NATO alliance: Mike Pence

US Vice President Mike Pence on Saturday said President Donald Trump would stand by the NATO transatlantic alliance and no one should doubt his commitment after sacrifices made to defend it.

"The president (Donald Trump) asked me to be here today to convey a message, a reassurance, the United States of America strongly supports NATO and we will be unwavering in our commitment to this transatlantic alliance," Pence told the Munich Security Conference.

"Let no one doubt our commitment," he said.

The Munich conference, attended by top leaders, officials and analysts from around the world, was watching Pence closely to see if he would reaffirm the central US role in world affairs after Trump's "America First" stance suggested Washington would strike out on its own.

Speaking just before Pence, German Chancellor Angela Merkel had warned countries against precisely that, saying the only way to solve global problems was to stick together.

"In a year in which we see unimaginable challenges we can either work together or retreat to our individual roles. I hope that we will find a common position," Merkel said.