CHARLOTTESVILLE, United States: Secretary of State John Kerry warned Wednesday against "senseless" spending cuts to diplomacy, saying the United States needed robust engagement to remain an "exceptional" nation.

In his first speech since taking over as the top US diplomat, the former longtime senator focused on the latest fiscal showdown between the White House and Congress and the threat of massive automatic spending cuts on March 1.

Declaring that "deploying diplomats today is much cheaper than deploying troops tomorrow," Kerry said: "In many ways the greatest challenge to America's foreign policy today is in the hands not of diplomats, but of policymakers in Congress."

"My credibility as a diplomat working to help other countries create order is strongest when America at last puts its own fiscal house in order -- and that has to be now," Kerry said at the University of Virginia.

"Think about it: It's hard to tell the leadership of any number of countries that they have to resolve their economic issues if we don't resolve our own," he said.

"Let's reach a responsible agreement that prevents these senseless cuts. Let's not lose this opportunity because of politics," he said.

Kerry delivered the speech four days before he heads off on his first foreign trip as secretary of state, visiting nine countries in Europe and the Middle East to reconnect with allies and discuss hotspots such as Syria.

Kerry, a former presidential candidate and the son of a diplomat, said that the United States had the ability to encourage stability around the world, preventing failed states that are "among our greatest security threats."

"America is not exceptional simply because we say we are. We are exceptional because we do exceptional things," Kerry said.

"We will continue to lead as the indispensable nation -- not because we seek this role, but because the world needs us to fill it... Not because we view it as a burden, but because we know it to be a privilege."

Kerry pointed to crises in Afghanistan, Pakistan and Mali as resulting from the international community losing interest. Kerry as a senator spearheaded a bill that authorized $7.5 billion over five years in civilian aid to Pakistan.

Pointing out that foreign affairs counts for only one percent of federal spending, Kerry vowed to fight on behalf of US businesses but also to promote US "values" and assistance in everything from AIDS to human trafficking.

"Foreign assistance is not a giveaway. It is not charity. It is an investment in a strong America and free world," he said.

"The State Department's conflict stabilization budget is about $60 million a year now. That's how much the movie 'The Avengers' took in on a single Sunday last May," Kerry said.

"The difference is, the folks that we have on the ground doing this job are actually real superheroes," he said.

Kerry, who as a senator unsuccessfully sought to pass legislation to curb greenhouse gas emissions, called passionately for international action to tackle climate change -- an effort opposed by the US Republican Party.

Kerry warned that without action, "rising temperatures and rising sea levels will surely lead to rising costs down the road."

"If we waste this opportunity, it may be the only thing our generations are remembered for. We need to find the courage to leave a far different legacy," he said.