NATO chief Jens Stoltenberg headed for Washington on Monday for the first time since US President Donald Trump was elected, holding talks with senior officials about defeating the Islamic State group, his office said.
Stoltenberg will meet US Defence Secretary James Mattis on Tuesday, then meet foreign ministers from the US-led coalition working to defeat IS, his office said in a statement.
He will also hold a series of unspecified meetings during the visit beginning later Monday and ending Tuesday, it added.
During a visit to NATO headquarters in Brussels last month, US Vice President Mike Pence said Trump expects NATO allies to make real progress by the end of this year towards meeting the increased defence spending target agreed by the alliance.
The transatlantic alliance set a goal in 2014 of raising defence spending to two percent of GDP over a decade.
So far, of the 28 NATO members, only the United States, Britain, Poland, Greece and Estonia have met the two percent target.
Mattis delivered a similar message at a NATO defence ministers meeting a week earlier, saying Washington could "moderate" its commitment if allies fail to pay up.