Defense Secretary Robert Gates' call to cut back on missile defense programs is running into resistance from lawmakers and others who say the U.S. will be left vulnerable in the face of North Korea and Iran's advancing efforts to develop long-range rockets. 

Gates called for $1.4 billion in cuts to missile defense as part of a budget plan he says will "reshape the priorities" of the Pentagon and "rebalance this department's programs in order to institutionalize and finance our capabilities to fight the wars we are in today and the scenarios we are most likely to face in the years ahead."

Among the proposed cuts would come the end of the "multiple kill vehicle" program -- a hovering machine meant to shoot down enemy missiles, even from space. 

Other high-tech missile defense programs would also be scaled back. The second prototype aircraft of the Airborne Laser -- a Boeing 747-mounted laser meant to intercept missiles near their launch areas -- would be terminated and the design efforts to date turned into research and development. 

Gates said he also would cancel plans to increase the number of ground-based interceptors in Alaska, a move opposed by Alaska's top officials, among others. 

"I can't emphasize enough how important it is that we continue to develop and perfect the global missile defense network. Alaska's strategic location and the system in place here have proven invaluable in defending the nation," Gov. Sarah Palin said in a statement, adding that North Korea's rocket program could threaten Alaska. 

Alaska Sens. Lisa Murkowski and Mark Begich were among six senators who signed a letter to Obama opposing the missile defense cuts, writing that such a "major reduction" could "undermine our emerging missile defense capabilities to protect the United States against a growing threat." 

"As you know, the threat from ballistic missiles is significant and on the rise," they wrote, citing North Korea's rocket launch, conducted in defiance of international warnings. 

They wrote that such cuts would leave the U.S. "less capable" of responding to missile threats. 

"The fact remains that our adversaries continue to invest large sums in the development of these weapons. The question is whether we respond by developing appropriate defenses against them," they wrote. 

Connecticut Sen. Joe Lieberman, who also signed the letter, told FOX News the Airborne Laser is a "really important program" since it gives the military the "unique capacity to hit a missile in boost phase before it even gets into its normal arc."

James Carafano, a defense analyst at the conservative Heritage Foundation, said complaints about cost overruns as it relates to the development of missile defense technology are short-sighted. 

"If you don't experiment you don't learn anything," he said. "This is the equivalent of telling the Wright Brothers, 'Dude, everybody wants bicycles -- what are you doing?'" 

Carafano said even though North Korea and Iran might operate immature missile systems now, they will continue to develop them while the U.S. loses ground under Gates' cuts. 

"There is no future of missile defense right now. The momentum has just stopped dead in its tracks," he said. 

Oliver North, Marine Corps lieutenant colonel and host of FOX News' "War Stories," said the administration needs these systems as a deterrent, adding that Obama's calls for a nuclear-free world simply are not realistic. 

"Countries like North Korea and Iran and Pakistan are not going to give up their nuclear weapons. You've got to be prepared to protect yourself," he said. "You cannot prevent the next war by disarming in this one." 

But Gates said his overhaul would in fact shift focus to the "rogue state" missile threat. 

"We will continue to robustly fund continued research and development to improve the capability we already have to defend against long-range rogue missile threats, a threat North Korea's missile launch this past weekend, reminds us is real," he said. 

Several lawmakers were quick to praise Gates' proposal as a balanced and realistic assessment of what the country can afford to keep funding. The overall budget plan calls for a shift away from high-tech weapons programs and toward more practical efforts like the fight against insurgents in Afghanistan. 

Benjamin Friedman, a research fellow in defense at the Cato Institute, said if anything, Gates' approach to missile defense was "timid." 

"It's not exactly as if we're throwing away our missile defense capability," he said, adding that the Airborne Laser and multiple kill vehicles have not yet proved effective. 

But Carafano said if Congress approves Gates' request, it'll be hard to reverse course to respond to developing threats abroad. 

"Even if we change minds in a year or two, we'll be way behind," he said. "I'm not thinking about today -- I'm thinking about five, 10 years from now." 

FOXNews.com's Judson Berger and FOX News' Molly Henneberg contributed to this report.