US Secretary of State Rex Tillerson pressed NATO allies Friday to ramp up military spending and denounced Russia's "ongoing hostility and occupation" of Ukraine as the Trump administration toughened its tone toward Moscow.
Russia declared itself "perplexed" by the comments from Tillerson, who met fellow NATO foreign ministers for the first time ahead of a May 25 summit to be attended by leaders of the 28-nation alliance, including President Donald Trump.
Without specifically taking aim at the top US diplomat, Russia's foreign ministry said NATO uses "the myth of the Russian threat, the slander of Russian aggression", to maintain unity.
For his part, Tillerson urged the NATO allies to agree at the May summit to produce plans by the end of the year to meet the spending pledge.
"As President Trump has made clear, it is no longer sustainable for the US to maintain a disproportionate share of NATO's defence expenditures," Tillerson said in Brussels.
NATO countries originally agreed at a summit in Wales in 2014 to contribute the equivalent of two percent of their gross domestic product to defence.
Seeking to draw a line under the funding row, NATO chief Jens Stoltenberg said NATO members understood they had to boost spending not so much to please Washington but to counter new threats from both the east and the south.
"One option we are examining is national plans to deliver on the commitments we have made," Stoltenberg told a press conference ending five hours of talks.
Tillerson's remarks, reinforced later by those from Defence Secretary Jim Mattis in London, were tougher on Russia than those previously made by Trump or his cabinet officials.
Trump had stressed the need to improve US relations with Moscow after they had sunk to a low under president Barack Obama over the crisis in Ukraine.
Tillerson told the alliance's forum with Ukraine co-chaired by Ukrainian Foreign Minister Pavlo Klimkin that "American and NATO support for Ukraine remains steadfast" in the wake of "Russia's aggression against Ukraine" three years ago when it annexed Crimea.
"Today, Russia's ongoing hostility and occupation is compromising our shared vision of a Europe that is whole, free, and at peace," Tillerson said.
He vowed that the US administraiton will keep sanctions in place until Russia reverses the actions that triggered them and oppose any further bid by Russia to redraw Ukraine's borders.
He also pressed Russia to fulfill its obligations under the Minsk agreements to end the war in eastern Ukraine, where he said "Russian-led separatist forces" are fighting Ukrainian government forces.
Klimkin, speaking to reporters afterward, accused Russia of "creeping annexation" in the Donbass region of Ukraine.
Allies have been alarmed at the prospect of Trump seeking to improve relations with Russia at the expense of support for the pro-Western government in Ukraine or NATO allies in former Soviet parts of eastern Europe.
Tillerson arrived in Brussels following a visit to Turkey, a NATO ally and key player in both Syria and Iraq where Washington wants to defeat the Islamic State jihadists.
In the last two years, IS has claimed or hailed a wave of deadly attacks in the United States and European cities, including Brussels.
Saying building "local capacity" is the best way to fight terrorism, Stoltenberg announced the alliance will increase aid to the Iraqi government by training medical personnel and staff who maintain armoured vehicles.
But the NATO funding row remains central.
NATO's 2016 annual report said only five countries met the two percent target -- the United States, Britain, Greece, Poland and Estonia -- while Washington still accounted for nearly 70 percent of combined alliance defence spending.
During a visit to NATO in February, Mattis voiced staunch support for NATO but warned that Washington could "moderate" its commitment if allies fail to pay up.
Trump said after a visit by German Chancellor Angela Merkel this month that Germany owes "vast sums of money" to NATO and the US.
But German Foreign Minister Sigmar Gabriel told reporters it was "totally unrealistic" for his country to meet the two-percent of GDP target.