From terrorism to the economic meltdown, problems menacing the United States' security and economy also threaten an increasingly interconnected world, President Barack Obama said yesterday.

"In this new century, we live in a world that has grown smaller and more interconnected than at any time in history," Obama said in his weekly radio and Internet address, taped during his first presidential trip to Europe. "Threats to our nation's security and economy can no longer be kept at bay by oceans or by borders drawn on maps."

Because no one nation can handle such threats alone, it is valuable for a president to make such trips "to strengthen and protect our nation", he said.

Economic problems overseas mean people in those countries cannot buy the goods produced in the United States, which means more lost jobs, he said.

"The only way out of a recession that is global in scope is with a response that is global in coordination," he said. "That is why I'm pleased that after two days of careful negotiation, the G-20 nations have agreed on a series of unprecedented steps that I believe will be a turning point in our pursuit of a global economic recovery." The countries are moving to get banks lending again and moving to tighten financial regulations, he said.

Common concerns extend well beyond the economy.

Obama spoke of discussions with Russian President Dmitry Medvdev and Chinese President Hu Jintao during his trip.

"President Hu and I agreed that the link between China's economy and ours is of great mutual benefit, and we established a new strategic and economic dialogue between the US and China," he said. "President Medvedev and I discussed our shared commitment to a world without nuclear weapons, and we signed a declaration putting America and Russia on the path to a new treaty to further reduce our nuclear arsenals."

Obama noted that he asked NATO allies for more help in Afghanistan. Yesterday, alliance members agreed to send up to 5,000 more military personnel there, the White House said.

"That is where al-Qaida trains, plots and threatens to launch their next attack," the president said.