Nato has asked Macedonia to join the Western bloc, with US leader Donald Trump giving Russia little to smile about so far.

"We have decided to invite the government in Skopje to begin accession talks to join the alliance," the 29 Nato leaders, including Trump, said in a joint communique at a Nato summit in Brussels on Wednesday (11 July).

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Macedonia will become "the 30th member" after it and Greece completed ratification of its new name, Nato head Jens Stoltenberg added.

"This is a once in a lifetime opportunity," he said, urging Macedonians to support the name deal with Greece in a referendum in autumn.

Nato expansion in the Western Balkans and former Soviet region is an anathema to Russia.

The Nato communique said Russia had used "hybrid actions" to try to stop Montenegro from joining last year, referring to a failed Russian coup there in 2016.

It had already carried out "some activities" in Macedonia designed to thwart the name deal, Macedonian leader Zoran Zaev said in Brussels.

Greece, the same day, also expelled two Russian diplomats on grounds that they were trying to wreck the accord, which ended objections that the name 'Macedonia' implied a claim to a Greek region of the same name.

The communique did not mention Georgia or Ukraine's Nato aspirations.

But Nato was "committed" to its "open door policy" in the long term, it said, with the Georgian and Ukrainian leaders both invited to the summit on Thursday.

The Nato meeting was dominated by Trump's clash with Germany on defence spending.

His aggressive tone sharpened divisions, posing questions on allied unity at a time of heightened tension with Russia.

Trump is also due to meet Russian president Vladimir Putin in Helsinki next week, amid concern that the US leader might make deals over Europe's head.

But the Trump-signed Nato communique stuck to Western orthodoxy on Russia's live and frozen conflicts in Europe.

Orthodoxy

"We reiterate our support for the territorial integrity and sovereignty of Ukraine, Georgia, and the Republic of Moldova within their internationally recognised borders," it said.

"In accordance with its international commitments, we call on Russia to withdraw the forces it has stationed in all three countries without their consent," it added.

"We strongly condemn Russia's illegal and illegitimate annexation of Crimea, which we do not and will not recognise," it also said.

"We have a strong position from the White House … about the non-recognition of the illegal annexation of Crimea," Ukrainian president Petro Poroshenko said on Thursday.

Trump has made U-turns before, for instance, when he retracted his signature, by tweet, from a joint declaration of the G7 club of wealthy nations last month.

But his hard talk on Russia ahead of the Putin meeting went further than the Nato communique.

Trump urged Germany to halt construction of the Nord Stream 2 (NS2) gas pipeline with Russia if it wanted continued US protection.

"Pipeline dollars to Russia are not acceptable!" he tweeted late on Wednesday.

The US would pursue sanctions against EU firms if they invested in the project, US officials added.

Nord Stream sanctions

"We have been clear that firms working in the Russian energy export pipeline sector are engaging in a line of business that carries sanctions risk," the US state department told the Reuters news agency on Thursday.

"We believe it [NS2] would undermine Europe's overall energy security and stability by providing Russia another tool for the political coercion of European countries, especially Ukraine. Russia understands that this project is dividing Europe, and is using that to its advantage," it added.

The hard line pleased Poland, the Baltic states, and Nordic countries, as well as Poroshenko, who oppose NS2.

Meanwhile, if Trump annoyed German chancellor Angela Merkel, she took it like water off a duck's back.

His surprise call for Nato allies to double their spending target from two percent of GDP to four percent of GDP also failed to discombobulate Nato head Jens Stoltenberg.

"Well, I'll focus on what we've agreed ... [which was] increasing defence spending to two percent," Stoltenberg said when asked on Trump's appeal.

"Even during the Cold War, Nato allies were trading with Russia," Stoltenberg added, blunting Trump's attack on Berlin-Moscow gas deals.

Western muscle

Nato and the US also pledged to create a new rapid-reaction force of tanks and jets to boost its Russia deterrent, Stoltenberg noted.

The alliance will open two new command HQs, one in the US and one in Germany, and increase personnel in Afghanistan and Iraq, he also said, in what he portrayed as a show of Western unity.

"A strong Nato is good for Europe and good for the United States. Two world wars and a Cold War taught us that we are stronger together than apart," he said.