German minister criticises Trump's 'America First' policy

German Foreign Minister Frank-Walter Steinmeier on Thursday criticised Republican US presidential candidate Donald Trump for his speech in which he said it would be "America First" if he is elected as US president.

Trump spoke about his foreign policy plan on Wednesday, the day after victories in the primaries of five northeastern states.

The New York billionaire said that if he were to be elected he will force American allies, which have benefited from a US defence umbrella, to pay more for US defence measures.

"The countries we defend must pay for the cost of this defence. If not, the US must be prepared to let these countries defend themselves. We have no choice," Trump said.

"I can only hope that the election campaign in the USA does not lack the perception of reality," Walter Steinmeier said, commenting on Trump's statement.

"The world's security architecture has changed and it is no longer based on two pillars alone. It cannot be conducted unilaterally," Steinmeier said, referring to Trump's idea of "America First."

Steinmeier said international crises could only be solved if superpowers such as US and Russia and others unite.

"No American president can get round this change in the international security architecture," he added, saying that this was why " 'America First' is actually no answer to that."