"Our foreign policy is a complete and total disaster. No vision, no purpose, no direction, no strategy," Trump said in his first major foreign policy speech here after he declared himself as a "presumptive nominee" when he won primaries in all the five States.
He alleged that Obama has weakened US military by weakening its economy.
"He has crippled us with wasteful spending, massive debt, low growth, a huge trade deficit and open borders. Our manufacturing trade deficit with the world is now approaching USD 1 trillion a year. We are rebuilding other countries while weakening our own," he said.
"We have made the Middle East more unstable and chaotic than ever before. We left Christians subject to intense persecution and even genocide. Our actions in Iraq, Libya and Syria have helped unleash ISIS. And we are in a war against radical Islam, but President Obama won't even name the enemy," he said.
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Attacking his Democratic counterpart Hillary Clinton, Trump said, "She also refuses to say the words 'radical Islam', even as she pushes for a massive increase in refugees."
"After Secretary Clinton's failed intervention in Libya, Islamic terrorists in Benghazi took down our consulate and killed our ambassador and three brave Americans. Then, instead of taking charge that night, Hillary Clinton decided to go home and sleep! Incredible," he alleged.
Trump said that because of Obama's foreign policies, "rivals no longer respect the US".
"In fact, they are just as confused as our allies, but an even bigger problem is that they don't take us seriously any more. When President Obama landed in Cuba on Air Force One, no leader was there to meet or greet him - perhaps an incident without precedent in the long and prestigious history of Air Force One," he said.
"He should have known the result before making such an embarrassing commitment. The list of humiliations goes on and on. President Obama watches helplessly as North Korea increases its aggression and expands even further with its nuclear reach," he said.
He alleged that Obama has allowed China to continue its "economic assault" on American jobs and wealth, refusing to enforce trade rules - or apply the leverage on China necessary to rein in North Korea.