Sen. John McCain talks with media after tour of CONSOL R&D Labs in South Park, Pennsylvania, 09 Jul 2008

U.S. Republican presidential candidate John McCain says Iran's missile tests demonstrate the need for a defense shield, while his Democratic rival Barack Obama says tough diplomacy with Tehran is the answer.

McCain Wednesday said the United States should cooperate with its European and regional allies to meet the threat posed by Iran, citing the planned missile defense program in the Czech Republic and Poland.

Obama, speaking on various television news programs, expressed his view that the U.S. should open up diplomatic channels with Iran, and provide incentives for Tehran to change its behavior.

He also suggested tightening economic sanctions, noting a

Sen. Barack Obama waves as he emerges from a meeting in Washington, 09 Jul 2008

recent report showing U.S. exports to Iran have increased during U.S. President George Bush's time in office.

On Tuesday, McCain responded to the report's findings that cigarettes were a major export to Iran, saying "maybe that's a way of killing them."  He quickly added that he meant the remark as a joke.

McCain has been criticized before for impromptu remarks that seemingly make light of tension with Tehran.

Last year, he responded to a question about whether the U.S. planned to attack Iran by singing a variation of a popular Beach Boys song called "Barbara Ann," changing the words to "Bomb Iran." 

Some information for this report was provided by AFP, AP and Reuters.