Presidential frontrunner Donald Trump has said halting the spread of Islamic extremism would be a priority of his administration if he is elected president.

"Containing the spread of radical Islam must be a major foreign policy goal of the United States and indeed, the world," Trump said in a foreign policy speech in Washington on Wednesday.

The 69-year-old said that if elected president, he would put American security "above all else". 

Ex-CIA director: Trump a recruiting sergeant for ISIL

"'America first' will be the major and overriding theme of my administration," Trump said.

Trump spoke the day after victories in five Northeastern states that moved him closer to capturing the Republican Party presidential nomination for the November 8 election.

He delivered a withering critique of Barack Obama's foreign policy, saying the Democratic president has let China take advantage of the United States and has failed to defeat the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).

He pledged to "shake the rust off America's foreign policy".

He accused Obama of failing to handle crises in the Middle East, saying the current administration was leaving a legacy of "weakness, confusion and disarray".

"We've made the Middle East more unstable and chaotic than ever before," Trump said. He singled out Democratic frontrunner Hillary Clinton's handling of the deadly attacks on a US compound in Benghazi, Libya.

Trump has been increasingly virulent in his remarks targeting Muslim Americans since the deadly Paris attacks, and again after the San Bernardino shooting attack in California.

Trump's advisers cast Wednesday's speech as the first in a series of policy addresses aimed at calming the nerves of Americans who worry that the businessman does not have the experience to handle the range of responsibilities that land on a president's desk.

Trump currently stands at 988 delegates, according to CNN's running estimate. Ted Cruz is a distant second with 568, while John Kasich increased his numbers only slightly, to 152.

Source: Al Jazeera