Democratic front-runner Hillary Clinton rebuked Republicans and defended Nato in a counter-terrorism speech after deadly attacks in Brussels.
Her comments contrasted sharply with her Republican counterparts, namely Donald Trump, who has suggested scaling back US commitments to Nato.
Mrs Clinton said the US should consult more deeply with Arab partners and stand with Europe in its time of need.
"Our European allies stood with us on 9/11. It's time to return the favour."
America should not turn its back on its allies, she said during remarks at Stanford University in California, and insulting them is not a good way to fight terrorism.
She addressed Mr Trump's calls to reinstate the use of torture and water boarding to glean information from those accused of terrorism.
"I am proud to have been part of an administration that outlawed torture," the former secretary of state said.
The deadly attacks in Brussels that killed more than 30 people are the "latest brutal reminder" that more must be one to defeat to so-called Islamic State (IS) militant group, she said.
The US and Europe should take a "harder look" at airport security protocols, and other "soft targets" that IS may attack.
Mrs Clinton also said proposal in Congress to make a national commission on encryption could help fight online radicalization.