Stoltenberg said that Canada and European members of North Atlantic Treaty Organisation have increased defence spending by 3.8 per cent in 2016 compared to the previous year.
"No longer can the American taxpayer carry a disproportionate share of the defense of Western values", Mattis said during a closed door meeting with the alliance's 27 other defense ministers. "If your nations do not want to see America moderate its commitment to this alliance, each of your capitals needs to show support for our common defence".
During his presidential campaign, Trump said NATO had become obsolete and threatened to decrease United States support to European NATO members who failed to fulfill their financial obligations, particularly related to defense spending. "The opportunities will also depend on developments in the Norwegian economy in the period", he said.
The US has been demanding for the past 20 years that NATO's European member states increase their defense spending to at least two percent of their GDP in order to facilitate the replacement of outdated military hardware and the purchase of new kinds of weapons mainly those produced by the US.
"It's in everyone's interest to resume dialogue between the intelligence agencies of the United States and other members of Nato", Putin said, addressing Russia's Federal Security Service (FSB).
The United States is supporting groups fighting the Islamic State in Syria while Russian Federation, which claims to be doing the same, has devoted most of its military assets in the war-torn country to target rebel groups fighting the Assad regime.
Mattis also spoke of the need to negotiate with Russian Federation "from a position of strength". "But at the same time, president Trump has in both phone calls also underlined the importance of a fair burden sharing". He added that Russian Federation must "live by worldwide law" and will have to "prove itself" before the US military will work alongside Russia's. The Russia collaboration was a possible idea, but during a press conference at NATO's Brussels headquarters, Mattis said that now is not the time for such a team effort.
Mattis said allies must establish a clear road map toward 2 percent spending levels - including financial milestones - sometime this year. Stoltenberg said that Latvia, Lithuania and Romania are moving towards the target, and Germany is also increasing spending, but noted that "some allies are still really struggling". Concerns have increased in the days since National Security Adviser Michael Flynn resigned after he admitted to misleading Vice President Mike Pence about discussions he had about US sanctions on Russia with the Russian ambassador before Trump took office.
"This is significant, but it is not enough", he said.
May travelled to Washington last month for a meeting with the new US President, in which she affirmed her commitment to making sure other European powers to reach the minimum spend. "So, we need to keep the momentum".