President Bush and European Union leaders say they are united on Iran and pledge to work together to resolve lingering differences on issues of trade and the fate of the U.S. detention camp at Guantanamo Bay, Cuba.
President Bush says when it comes to the dispute over Iran's nuclear intentions, international cooperation is crucial.
"It is very important for the leadership in Iran to look at the world and say Europe and the United States and Russia and China are united in our common desire to make sure the Iranians do not develop a nuclear weapon," said Mr. Bush.
The president points to the international package of incentives handed to Iran in an effort to convince it to suspend nuclear enrichment. Iran has said it wants until late August to respond. Mr. Bush says that is too long, stressing once again that Tehran has weeks, not months to reply.
"It should not take the Iranians that long to analyze what is a reasonable deal," added President Bush.
The president spoke at a news conference at the end of the U.S-EU summit, along with European Commission President Jose Barroso and Austrian Chancellor Wolfgang Schuessel, whose country holds the revolving EU presidency.
Both men have raised concerns about the treatment of terror suspects held at the U.S detention center at Guantanamo Bay, Cuba. President Bush said he told them he wants to shut Guantanamo down as soon as a plan is in place to send some of the detainees back to their homelands and put others on trial.
"There are some that need to be tried in U.S. courts. They are cold blooded killers. They will murder somebody if they are let out on the street and yet we believe there ought to be a way forward in a court of law, and I am waiting for the Supreme Court of the United States to determine the proper venue in which these people can be tried," he said.
The troubled state of world trade negotiations was another thorny topic in Vienna, but European Commission President Barroso left sounding optimistic.
"After the good exchange of views we had today during this summit, I am convinced, I am really convinced that it is possible to have a really successful outcome of the Doha talks," said Mr. Barroso.
The mood of the three summit participants was clearly upbeat. But there were signs of tension when a reporter asked President Bush about a new public opinion survey that shows the image of the United States is declining in Europe. His question prompted an emotional response from the Austrian chancellor.
"I was born in '45. At that time, Vienna and half of Austria laid in ruins. Without the participation of America, what fate would have had Europe [what would have been Europe's fate]? Where would Europe be today?" replied Mr. Schoessel.
On the issue of North Korea, Mr. Bush said it faces further isolation from the international community if it test fires a long-range missile believed capable of reaching the United States.
Security was tight near the summit site - the historic Hofburg palace. Helicopters flew overhead and extra police were on the streets, but promised demonstrations during the meetings were small.
Hundreds of protesters gathered at the city train station early in the morning. Organizers said they expected a much larger crowd at the same spot later in the day, while Mr. Bush was winding up his stay in Vienna.
His next stop is Budapest, where he will commemorate the 1956 Hungarian uprising against communism that was crushed by Soviet troops. He will deliver the major speech of the trip in Budapest. White House officials say the theme will be the power of democracy and freedom.