U.S. Secretary of State Rex Tillerson, meeting with his NATO allies' counterparts, said Friday in Brussels that they must increase their countries' defense budgets.
The top U.S. diplomat told the foreign ministers the alliance must have "all of the resources, financial and otherwise, that are necessary for NATO to fulfill its mission" in places like Iraq and Syria.
Tillerson also addressed Russian aggression in Ukraine with remarks that were tougher than those previously made by the administration of U.S. President Donald Trump, which has stressed better relations with Russia.
"We want to have a discussion around NATO's posture in Europe, most particularly in eastern Europe in response to Russia's aggression in Ukraine and elsewhere," Tillerson told reporters.
In London Friday, U.S. Defense Secretary Jim Mattis, meeting with his British counterpart, also expressed concern about Russia. Mattis told reporters at a news conference Russia has been interacting with Taliban fighters in Afghanistan.
"We have seen Russian activity vis-a-vis the Taliban," Mattis said.
Mattis also expressed concern about "reckless" actions involving North Korea's nuclear weapons and missile programs, as he quickly pivoted to North Korea in response to a reporter's question about Iran.
"In the larger scheme of things," Mattis said North Korea is the more urgent threat.
"This is a threat of both rhetoric and growing capability," Mattis said. He added that North Korea's reported preparation of a nuclear test has "got to be stopped."
In addition to NATO resources, Secretary of State Tillerson said his most urgent matters were NATO's fight against terrorism and the alliance's posture in Europe, "most particularly Eastern Europe in response to Russia's aggression in Ukraine and elsewhere."
Tillerson's visit to Brussels comes one day after meeting with top Turkish officials in Ankara.
Tillerson hailed Turkey as a trusted ally after meeting with Turkish President Recep Tayyip Erdogan and other leaders Thursday.
He also underlined the importance of Turkey in the battle against Islamic State.
But the two NATO allies remain at loggerheads over Washington's support for the Syrian Kurdish group the PYD and its militia, the YPG, in fighting Islamic State militants. Ankara accuses the PYD of being a terrorist organization affiliated with the PKK, which is fighting the Turkish State.
In a joint news conference, Turkish Foreign Minister Mevlut Cavusoglu stressed Turkey's opposition to support of the PYD, but did not directly criticize the Trump administration.
Tillerson acknowledged no breakthrough on the dispute, saying more discussions are needed. "We are exploring a number of options and alternatives," he said while reiterating Washington's support of Ankara in fighting the PKK.
With Washington stepping up its military support of the YPG before the operation to liberate Raqqa, the self-declared capital of Islamic State, Ankara increasingly appears resigned to the fact that its call for its military forces to replace the Syrian Kurdish groups has been rejected.
But a presidential source ruled out any retaliatory measures against the United States, stressing Turkey did not want the issue to undermine future cooperation.