Barack Obama and John McCain stepped up their battle over foreign policy credentials Wednesday, with Obama accusing his rival of using fear to win votes and the McCain camp accusing Obama of wanting to fight terrorism with lawyers.

With shades of the 2004 presidential election showing through, the two presumptive nominees are using the war on terror as a campaign wedge.

McCain's camp increasingly is painting Obama as naïve for playing defense against an enemy that, McCain says, must be confronted head on. Obama's campaign is painting McCain as fear-mongering, defending a flawed strategy in Iraq at the expense of the broader war on terrorism.

"He's going to use predictable, petty and divisive attacks to try to score a few political points on national security," Obama said Wednesday. "If these attacks seem familiar, it's because they are. They come from the same tired political playbook that George Bush and Karl Rove have used for eight years."

Obama is stressing that terrorists must be fought within legal confines, and he said that the United States would have to follow such guidelines even in the prosecution of Usama bin Laden, if he is caught alive. He said bin Laden must not become a "martyr" if captured.

"I think what would be important would be for us to do it in a way that allows the entire world to understand the murderous acts that he's engaged in and not to make him into a martyr," Obama said, "and to assure that the United States government is abiding by basic conventions that would strengthen our hand in the broader battle against terrorism."

Obama supported last week's Supreme Court decision that Guantanamo Bay detainees have the right to challenge their confinement in civilian courts, while McCain and his supporters blasted the decision.

McCain said Wednesday that Obama wants to give bin Laden "habeas corpus rights, so we have a fundamental disagreement about it."

"He doesn't have an understanding of the nature of the threat," he said.

"I think that the American people will agree with me that these are enemy combatants, that we passed legislation with an overwhelming majority of the Congress, which he opposed that set up military commissions and commissions that would address and give some rights to the enemy combatants who were being held, but certainly not in a radical departure from history and to want to give them the same rights that citizens have in this country," McCain said.

His foreign policy under fire, Obama also held his first ever meeting Wednesday with his Senior Working Group on National Security, a 13-member group that includes former members of Congress and Clinton administration officials.

Republicans accuse Obama of believing counterterrorism is sometimes best handled as a criminal matter after he implied during an interview earlier this week that the court system can manage the aftermath of a terrorist attack.

Obama said on ABC's "Nightline" that after the 1993 World Trade Center attacks, "we are able to arrest those responsible, put them on trial.

"They are currently in U.S. prisons - incapacitated," he said.

Obama is defending that position, arguing that the Bush administration's reaction to the Sept. 11 attacks, specifically war in Iraq, was a wrong-headed over-reaction that made the world less safe.

"Senator McCain's campaign has said I want to pursue a law enforcement approach to terrorism," he said Wednesday. "This is demonstrably false, since I have laid out a comprehensive counter-terrorism strategy that includes military force, intelligence operations, financial sanctions and diplomatic action."

But Obama has made numerous statements critics say betray a weak understanding of the terrorist threat.

The McCain campaign argues Obama's comments about turning to the courts represent a "September 10th mindset," and that traditional law enforcement cannot be effective without efforts to strike at terrorists overseas.

Polls show McCain has a double-digit lead over Obama when it comes to which candidate voters think is most able to combat terrorism. McCain is trying to press his advantage.

The McCain camp enlisted former New York Mayor Rudy Giuliani, a former GOP rival who accused Obama of playing defense in the war on terror in a conference call Wednesday.

"Democrats want to go back to a pre-Sept. 11 view of terrorism - what I call being on defense. They want to treat it mostly as a criminal justice matter, use grand juries' investigations," Giuliani told FOX News Wednesday. "I would just describe it and just say this is not a realistic approach. Time has proved that being on offense is better than being on defense."

In response, Democratic Sen. Joe Biden released a statement saying: "It's no surprise that it takes a man with zero national security and foreign policy experience to defend the policies of John McCain and President Bush."

FOX News' Carl Cameron, Shushannah Walshe and Bonney Kapp contributed to this report.