Democratic presidential nominee John F. Kerry on Wednesday assailed President Bush's plan to dramatically reduce the number of troops stationed around the globe, calling the realignment a potential threat to the nation's security.

"Nobody wants to bring the troops home more than those of us who have fought in foreign wars. But it needs to be done at the right time and in a sensible way," Kerry said in an address to the Veterans of Foreign Wars, the same organization to whom Bush pitched his plan Monday to recall as many as 70,000 troops from Cold War-era bases in Europe and Asia.

Further escalating the campaign battle over national security, Kerry said that it is particularly wrong-headed to pull a third of the U.S. ground troops from South Korea.

"Why are we unilaterally withdrawing 12,000 troops from the Korean Peninsula at the very time we are negotiating with North Korea -- a country that really has nuclear weapons? This is clearly the wrong signal to send at the wrong time," Kerry said.

Kerry maintained that the Bush proposal would also reduce forces at a time when the United States is battling al Qaeda in 60 countries. "Let's be clear -- the president's vaguely stated plan does not strengthen our hand in the war against terror," he said. "And in no way relieves the strain on our overextended military personnel. It doesn't even begin until 2006, and it takes 10 years to achieve. This hastily announced plan raises more doubts about our intentions and our commitments than it provides real answers."

In response, the Bush-Cheney campaign sent out a statement by retired Gen P.X. Kelley, former commandant of the Marine Corps, and it organized a teleconference with Sen. John W. Warner (R-Va.), chairman of the Armed Services Committee, both of whom support the plan.

"John Kerry's opposition to troop realignment demonstrates a backward-looking view that blindly embraces the status quo and ignores the realities of the post-9/11 world," Kelley said. "The threat America faces today is fundamentally different than the threats America's military was configured to face during the Cold War."

Bush's troop realignment plan is part of a broad military shift that administration officials say will make U.S. forces more flexible at a time when national security threats are less predictable. Over the next decade, about a third of the 230,000 soldiers based overseas would return to bases at home, and massive military facilities in Germany and other allied nations would be downsized or closed. Smaller, lightly staffed bases and supply stations would be established in Eastern Europe. They could be used for rapid deployments to the Middle East or other trouble spots.

Kerry received his most enthusiastic response from 6,000 VFW members when he strongly advocated improving health care, disability and other benefits for veterans. But overall, he was received here far less enthusiastically than was Bush, who generated two standing ovations during his speech. By contrast, Kerry's audience offered cordial and polite applause, with one detractor heckling the Massachusetts senator.

Both campaigns are assertively courting the nation's 26 million veterans, a traditionally Republican constituency with which Democrats hope they can make gains because of Kerry's military record. The VFW has 2.6 million members.

After the speech, a number of veterans said that they believe the Democrat is promising far more than he could deliver. "John Kerry said exactly what veterans wanted to hear today," said Alan Hall, a Navy veteran of World War II and the Korean War. "But how is he going to pay for it all?"

Robert Belding, a Persian Gulf War veteran, said he boycotted the speech because Kerry's "promises don't reflect his Senate record. He says he supports troops, and then he votes against the $87 billion request to help them."

The comments of some veterans indicated that GOP efforts to paint Kerry's commitment to national security as new and politically expedient are resonating.

"I heard he missed 75 percent of his votes on the intelligence committee," said World War II veteran Gerald Kulligan, echoing the e-mails being sent out by the Bush campaign. "Who wants a president who works 25 percent of the time?"

Some said they have not forgiven him for protesting the Vietnam War when he returned from the war in 1969. "That was a bad time for guys coming back, and he come back and was hooked with Hanoi Jane," said Elmo Pennington, a Vietnam War veteran, referring to Jane Fonda's war protests. "He never made no friends with that."

Still, others here mobbed Kerry at the stage and praised his push for veterans benefits and his comments protesting the troop realignment. "As a Korean War veteran, I don't think we can pull out of Korea," said Jack Carney of Florida.

Kerry in the past 10 days has been put on the defensive on national security with a barrage of partisan challenges to his Vietnam service record, his war wounds, his commendations for valor and his fitness to serve as commander in chief.

Clearly trying to recapture his voice on an issue that figured heavily at the Democratic National Convention last month -- his military service during the Vietnam War and his commitment to soldiers -- Kerry talked about his Senate work on Vietnam prisoners of war and the missing in action, and repeatedly tried to identify with the group, of which he is a member.

He also twice mentioned Sen. John McCain (R-Ariz.), a decorated Vietnam War veteran who campaigned with Bush recently. Kerry pointed out that in a Senate hearing on Tuesday, McCain questioned the troop plan, saying, "I'm particularly concerned about moving troops out of South Korea when North Korea has probably never been more dangerous than any time since the end of the Korean War. I hope, as some critics allege, this is not a retreat to fortress America."

In discussing benefits, Kerry pledged to take care of those who serve, advocating better health care by keeping VA hospitals open.

He also reiterated his pledge to ensure that veterans can draw their pensions and disability benefits simultaneously. Today, veterans must give up a dollar of their pension for every dollar of disability assistance that they receive.

"In recent days, you have heard from some who have claimed that the job is getting done for veterans," Kerry said. "Well, just saying the job is getting done doesn't make it so."

John F. Kerry talks to veterans addressed by President Bush on Monday.