US President Donald Trump will host NATO chief Jens Stoltenberg in Washington at a time of severe strain within the Atlantic alliance, the White House announced Saturday.

NATO chief Jens Stoltenberg on Wednesday welcomed a pullback by the Ukrainian army and Moscow-backed separatists in eastern Ukraine, but reiterated calls for Russia to "withdraw all their troops".

NATO "fully supports" American efforts to find peace in Afghanistan, the alliance chief said Tuesday after talks with US Secretary of State Mike Pompeo on a deal taking shape with the Taliban.

NATO will this week decide how to respond to Russia's violation of a key Cold War arms treaty, alliance chief Jens Stoltenberg said Tuesday, insisting any measures would be defensive.

NATO Secretary General Jens Stoltenberg on Monday reiterated the bloc's commitment to grant former Soviet republic Georgia eventual membership despite Moscow's fierce opposition.

NATO Secretary General Jens Stoltenberg announced Wednesday that he will hold talks with Russian Foreign Minister Sergei Lavrov this week, as part of efforts to save a key arms control treaty that is on the point of collapse.

NATO will hold an emergency meeting with Ukrainian officials at alliance headquarters in Brussels on Monday over the naval standoff with Russia off the coast of Crimea.

Norway hosts NATO's biggest exercises since the end of the Cold War from Thursday, to remind Russia the Alliance stands united despite seeds of doubt planted by US President Donald Trump.

Russian intelligence was spying on former double agent Sergei Skripal and his daughter Yulia for at least five years before they were poisoned in a nerve agent attack, Britain's National Security Adviser Mark Sedwill said in a letter to NATO on Friday.

NATO chief Jens Stoltenberg on Tuesday warned the EU its new defence cooperation pact must not undermine the alliance, as US officials voiced fresh concerns about the flagship initiative.

The head of NATO on Monday praised embattled US Secretary of State Rex Tillerson for his "key role" in the North Korea crisis as rumours swirl that his position is under threat.

NATO Secretary General Jens Stoltenberg said Sunday that North Korea's nuclear and missile programme represented a "global threat and requires a global response".