Declaring it time to "shake the rust off", the Republican presidential frontrunner has accused Barack Obama of making the United States look weak internationally.
But the White House has defended its record in keeping the US safe.
It was to be a speech to stamp the billionaire businessman as more than just a showman.
But when Donald Trump ventures into foreign policy, Americans have come to expect the odd pronunciation hiccup ....
"Look at what happened in the 1990s. Our embassies in Kenya and Tanzania were attacked."
Hazy on the names of East African nations like Tanzania, perhaps, but Donald Trump is leaving no doubts when it comes to his thoughts on his country's international allies.
"Our allies are not paying their fair share. Our allies must contribute toward the financial, political and human costs of our security burden. but many of them are simply not doing so. They look at the United States as weak and forgiving and feel no obligation to honour their agreements with us."
In a wide-ranging speech, Mr Trump also called for more "unpredictability" in US foreign policy.
He vowed to walk away from any deals with Russia that aren't in America's interests, to play tough with China and to quickly eliminate the self-proclaimed Islamic State.
There were few details about just how these aims would be achieved and his heavy criticism of the Obama Administration prompted an immediate response from White House spokesman, Josh Earnest.
"I think when it comes to this president's foreign policy, there is no denying that the United States is safer and stronger than we were when President Obama took office back in January of 2009. What we have also seen is a strengthening of our alliances around the world. So, the President has a strong record to run on."
Campaigning in Indiana, Donald Trump's main Republican rival, Ted Cruz, also took aim, focusing his attack on the policy similarities between the real estate tycoon and Democrat frontrunner Hillary Clinton.
"Washington and New York want this general election to be between two rich, liberal New Yorkers who agree on virtually every issue. It is not surprising that Washington and New York want both of the candidates, the supposed Republican and the Democrat, to be supporters of Hillary Clinton's presidential campaign. That's called 'heads I win, tails you lose.'"
The Texas senator surprised many by revealing his running mate would be a candidate who retired from the Republican race earlier this year, Carly Fiorina.
"Hello Indiana!! Today I am very proud and very humbled and honoured to announce that I have accepted Senator Ted Cruz's offer to be his Vice President for the Republican nomination."
It's unusual for a presidential hopeful to announce a running mate before actually winning the party's nomination, but suggests Ted Cruz is confident Donald Trump will fall short of the required number of delegates to seal victory before the Republican convention in July.
And the Trump campaign continues to divide Americans across the United States, with at least five people, including children, hit by pepper spray in jostling between Trump supporters and opponents during a rally in California.
Share
