US Presidential candidates Donald Trump and Hillary Clinton clashed over national security again on Friday, with Trump calling his Democratic rival "trigger-happy" and Clinton arguing his proposals would make the world a more dangerous place.

The two White House hopefuls have waged a running battle this week over who is best placed to command the world's most powerful military, with both touting their support from retired military leaders and attacking their opponent's temperament and judgment.

Trump also injected drama into the national security debate this week by wholeheartedly endorsing Russian President Vladimir Putin as a strong leader who has fared better than U.S. President Barack Obama. Clinton, many Democrats and even some in his own Republican party balked.

Trump, speaking on Friday at the conservative Value Voters summit in Washington, painted Clinton as a "massive failure" while she was America's top diplomat from 2009 to early 2013,blaming her for the current turmoil in the Middle East.

"The problem is, Hillary Clinton is trigger-happy. Her tenure has brought us only war, destruction and death. She's just too quick to intervene, invade, or to push for regime change," he said at the summit.

Meanwhile in New York, Clinton met with national security and foreign policy experts who are supporting her campaign to discuss terrorism. She touted the bipartisan nature of the meeting and vowed to work across the aisle as president to tackle national security challenges.

"The nominee on the other side promises to do things that will make us less safe," Clinton told reporters at a news conference on Friday afternoon. "National security experts on both sides of the aisle are chilled by what they're hearing from the Republican nominee."

Both candidates are hoping to capitalize on concerns about national security and paint their opponents as unqualified leading into the Nov. 8 presidential election.

WORKING WITH THE RUSSIANS

Trump's speech on Friday comes after the candidate took the unusual step of criticizing U.S. policy in a program aired on Thursday night on Russian government-funded television network, RT, a 24-hour news channel that broadcasts in both English and Russian. He said he disagreed with the U.S. decision to invade Iraq in 2003 and that Obama botched the withdrawal.

"It's a war we shouldn't have been in, number one," Trump said in the interview. "And it's a war that, when we got out, we got out the wrong way. That's Obama."

Critics of the network, which mostly targets audiences outside of Russia, have described it as a propaganda arm of Putin's government.

American presidential candidates are not prone to condemn their country before a foreign audience, even if they are fierce critics of the current administration while campaigning in the United States. Trump has said far worse about Obama in appearances on U.S. television networks.

Clinton blasted Trump for appearing on the network and praising Putin, as he had done on Wednesday night during a televised national security forum.

"Every day that goes by this just becomes more and more of a reality television show," Clinton said. "It's not a serious presidential campaign, and it is beyond one's imagination to have a candidate for president praising a Russian autocrat like Vladimir Putin."

The White House said it had no comment on Trump's remarks.

The New York businessman also said on RT on Thursday he did not think Russia's government was behind the hack of Democratic National Committee email servers, and doubted it was trying to interfere in the U.S. election. Experts inside and outside the government have pointed to Russian-backed actors as the source of the hack, which has been used to leak information in an attempt to embarrass Democrats.

Trump, in his speech on Friday, stuck to his belief that the United States and Russia can work together to defeat Islamic State militants. He said any nation that wants to join the United States against ISIS is welcome.

"That includes Russia," he said. "If they want to join us in knocking out ISIS, that's just fine as far as I'm concerned."

Trump also sought on Friday to blame Clinton after reports that North Korea had tested a nuclear weapon, arguing it was the fourth such test since the Democrat became secretary of state in 2009 and that she should have ended the nation's nuclear program before her tenure ended.

"It's just one more massive failure from a failed secretary of state," Trump said.

Clinton called the North Korea test "outrageous and unacceptable," saying she supports imposing additional U.S. and United Nations sanctions.

"It will be on the top of my list in dealing with China on how we're going to prevent what could very well be a serious conflict with North Korea," she said. – Reuters