By Robin Emmott
BRUSSELS (Reuters) - The European Union must learn to speak with one voice on the international stage and also develop a "military capacity to act" or slide into irrelevance, eclipsed by Washington and Beijing, its incoming foreign policy chief said on Monday.
The EU, with a total population of more than 500 million, accounts for more than 20% of global economic output and is the world's biggest aid donor, wielding considerable "soft power".
But its complex institutional arrangements and the competing priorities among its 28 member states have long checked its influence in foreign and security policy.
The decision of Britain to leave the EU, Washington's withdrawal from the 2015 Iran nuclear accord and Europe's failure to help stabilise neighbours from the Caucasus to the Sahara have further undermined the EU's global clout.
Josep Borrell, Spain's foreign minister who was picked by EU leaders in July to become the bloc's top diplomat from Nov. 1, said Europe must now back up its rhetoric with decisive action or be increasingly sidelined by other global players.
"I am convinced that if we don't act together, Europe will become irrelevant," Borrell told the European Parliament in a confirmation hearing, calling for more EU joint spending on defence and a greater willingness to deploy EU battlegroups.
Faced with an increasingly powerful and assertive China and a United States under President Donald Trump pursuing an "America First" agenda, Europe must try much harder to make its voice heard and to defend its interests, he said.
"Europe has to position itself among the growing confrontation between the U.S. and China... we have to promote our own approach," he said, alluding to the trade war and increased geopolitical rivalry between Washington and Beijing.
Borrell, a 72-year-old veteran of EU politics who will replace Italy's Federica Mogherini, said the U.S.-led NATO alliance would remain the bedrock of European security but added: "There is no certainty about the international role of the United States."
The EU and Washington disagree on a range of international issues, including Iran, and Trump has publicly chided European countries, especially economic powerhouse Germany, for not spending more on their own defence.
Acknowledging that the EU foreign policy post, which tries to meld the competing ambitions of 28 governments, was "mission impossible", Borrell said his priority would be the six Balkan states - Serbia, Kosovo, Montenegro, Albania, Bosnia and North Macedonia - which aspire to join the bloc one day.
Borrell said his first foreign trip would be to Kosovo, whose independence Spain has not recognised due to concerns about fanning the ambitions of separatist Catalans.
"We cannot be a global actor if we cannot resolve our problems at home," he said.
The Balkan states are struggling to meet EU standards on the rule of law and tackling corruption but must also contend with growing reluctance among some member states to take in new members while existing problems remain unresolved.
Borrell said other priorities for his five-year term were stronger EU arms export controls, a policy to stabilise Libya and maintaining EU sanctions on Russia, imposed over Moscow's seizure of Crimea and its support for separatists in Ukraine.
In his new role, Borrell will be a member of the executive European Commission which draws up laws and helps set policy for the bloc. Its incoming president, Ursula von der Leyen, a German, has said reversing the EU's waning influence as an open, free-trading, democratic bloc will be a priority for her team.
(Editing by Gareth Jones)