John Kerry used his first public speech as US secretary of state on Wednesday to urge US citizens to support diplomacy, saying that automatic cuts to the federal budget would hurt the country at home and abroad.

"I came here purposefully to underscore that in today's global world, there is no longer anything foreign about foreign policy," he told a packed auditorium at the University of Virginia, which was founded by Thomas Jefferson, the first US secretary of state.

Kerry cited a number of diplomacy's benefits for the United States, including trade, jobs, peace and the spread of American values.

"Before (Richard) Nixon's bold opening with China, no one could have imagined that today it would be our second-largest trading partner, but that's exactly what's happened," he said, referring to the then-president's historic 1972 trip to China.

Less than three weeks after taking the oath as the top US diplomat, Kerry defended the need for foreign aid even in the face of budgetary pressures.

The former senator from Massachusetts urged his former colleagues in Congress to reach a budget deal with President Barack Obama to avoid the automatic implementation on March 1 of spending cuts across nearly the entire US government through a procedure known as sequestration.

"Foreign assistance is not a giveaway; it is not charity. It's an investment in a strong America and a free world," he said, later warning against "senseless" reductions in State Department funding.

"Eleven of our top 15 trading partners used to be the beneficiaries of US foreign assistance. That's because our goal isn't to keep a nation dependent on us forever. It's precisely to create these markets, to open these opportunities, to establish rule of law.

"Our goal is to use assistance and development to help nations realize their own potentials, develop their own ability to govern and become our economic partners."

Kerry, as State Department officials often do, pointed out that despite public perception that the figure is much higher, overall US spending on foreign affairs is just over 1 percent of the national budget.

"Deploying diplomats today is much cheaper than deploying troops tomorrow," he said. "We need to remember that."

He said free-trade talks that Obama announced last week between the US and the European Union will form the world's biggest bilateral trade relationship.

"Our work is far from over," Kerry said. "Seven of the 10 fastest-growing countries are on the African continent. And China, understanding that, is already investing more than we do there."

According to the State Department, the cuts ― authorized by Congress in the Budget Control Act of 2011 ― would jeopardize $2.6 billion in foreign aid, security assistance and other international programs.

Kerry made his speech just four days before he makes his first trip abroad as secretary of state. His travels, from Sunday to March 6, cover nine countries in Europe and the Middle East, State Department spokeswoman Victoria Nuland said on Tuesday.

Kerry will fly first to London and then Berlin, where he lived as a child. In Paris, Kerry and French officials will discuss the Islamist insurgency in Mali. He is then scheduled to visit Rome for multilateral meetings on Syria as well as a meeting with leaders of the Syrian Opposition Coalition. That will be followed by trips to Turkey, Egypt, Saudi Arabia and the United Arab Emirates before he ends his travels in Qatar for talks on bilateral and regional issues.

Nuland said, "He is characterizing this first trip more broadly as a listening tour." Unlike Hillary Clinton's first trip as secretary of state ― to Japan, the Republic of Korea, China and Indonesia ― Kerry, by visiting Europe, hopes to assure US allies on the continent of their importance. Some said Kerry hasn't been enthusiastic about the policy of the US "pivot" toward Asia, especially its military component, analysts said.