US President Donald Trump blasted Germany anew over trade and defense, ratcheting up a dispute with Chancellor Angela Merkel that risks getting personal and undermining a trans-Atlantic bond that is the bedrock of US-European relations.

Mr Trump's comments came in an early-morning tweet on Tuesday issued just as Mrs Merkel hosted Indian Prime Minister Narendra Modi in Berlin, where they held a joint cabinet meeting and signed cooperation agreements.

"We have a MASSIVE trade deficit with Germany, plus they pay FAR LESS than they should on NATO & military," the US president posted on Twitter. "This will change."

The message came minutes after Mrs Merkel and Mr Modi held a joint press conference in which the German leader called India a "reliable partner with respect to big projects." That contrasted with her comments in Munich on Sunday that dependable trans-Atlantic ties that formed the basis of German foreign policy since World War II "are to some extent over."

Mr Trump's tweet showed the deterioration of links with a key NATO ally, yet his timing also highlighted Germany's web of relations with international partners who broadly share Mrs Merkel's free-trade outlook and conviction on combating climate change. After hosting Mr Modi, Mrs Merkel is due to meet with Chinese Premier Le Keqiang on Thursday.

Alongside Mr Modi, Mrs Merkel said that while trans-Atlantic relations are of "paramount significance," the European Union had to forge its own path in the world "considering the current situation."

"What I said was simply to indicate that, here are even more reasons beyond those we already have that Europe needs to take its destiny into its own hands," she said.

Mr Modi, the prime minister of the world's largest democracy, welcomed a stronger global role for the EU and expressly lauded the bloc's most powerful leader.

"We always want that the European Union should be stronger, should be more active," Mr Modi said. "Through Chancellor Merkel, we will be able to work with the European Union. It's very easy for us."

After failing to convince Mr Trump to commit to the global Paris climate accord at a Group of Seven summit over the weekend, Mrs Merkel has turned her attention to forging consensus among other G20 nations at a summit meeting she's hosting in Hamburg in July.

Mr Modi signalled that India will move forward on its climate agenda even if the US exits the Paris agreement, saying politicians have "absolutely no right" to put in jeopardy the environment for future generations. He praised Mrs Merkel's experience and Germany's economic example to India.

"We are meant for each other," Mr Modi said.

Bloomberg