MANCHESTER — Mitt Romney said Monday that Texas Gov. Rick Perry's suggestion of sending U.S. troops to Mexico to help fight the drug war is “a bad idea.”

“Let's build a fence first, and let's have sufficient border patrol agents to protect it,” Romney said Monday in an interview with the New Hampshire Union Leader. “And if the Mexican government wants us to help it with logistics, intelligence, satellite images, I'm sure we can provide the sort of support we provided in Colombia.”VIDEO: Mitt Romney interview with Union Leader

Romney said military spending should be at least 20 percent of the federal budget, “an appropriate level of spending for a nation that sees the world with a number of very threatening forces in it.”

He cited China, which, he said, wants to “expand control into the South China Sea,” has its “eyes on Taiwan” and has “already seized Tibet.”

He cited “the Jihadists'” aggression against the United States and said Russia is “trying to rebuild parts of or elements of the old Soviet Union.” He said Iran is “about to become nuclear” and Pakistan “could easily become a failed state.

“So to pull back on our military, to me doesn't make sense,” he said.

Romney said the U.S. Navy is smaller than it has been since 1917, while “our soldiers are on multiple rotations and are stretched extraordinarily thin.”

“You need more troops, more ships, you need a more modern Air Force and you have to give the care to our veterans that come home,” said Romney.

“It should remain at least 20 percent of our federal budget,” he said.

Stimulus, deficit

Romney said he supported a Republican version of a stimulus package several years ago, but opposed President Barack Obama's plan.

“The stimulus was an effort to try to keep us from going over the waterfall economically,” Romney said. “We already went over the waterfall.

“We're now looking for a dramatic overhaul of the American economy to go from an anti-business, anti-investment approach to a pro-business, pro-jobs approach.

“I'm not in favor of a new stimulus,” said Romney, “but I will say that when the last stimulus was crafted, $787 billion borrowed, the fact that we didn't use virtually any money to provide for armament for our troops, for weapons systems to do combat, I find incomprehensible.”

A deficit reduction commission in Washington must draft a $1.5 trillion deficit reduction plan that can win congressional approval by Thanksgiving. If it does not, more than $1 trillion in across-the-board spending cuts, including $400 billion from the military, will go into effect.

Including military cuts in the equation would be “a grave mistake,” especially during “a time of war,” said Romney.

Afghan independence

Romney said that at some point Afghanistan, on its own, must “earn and keep its independence from the Taliban.

“It is time for the Afghan troops to take that responsibility. We will not stay there protecting their independence forever,” he said.

He said the generals in the theater have said the U.S. can pull back its surge troops in December 2012. Obama has pushed the date up to September 2012, “which I think is a mistake, based on politics. I think it puts our troops in greater danger.”

He noted the generals say the Afghans will be fully ready to assume responsibility in 2014.

“Do I look at that with 100 percent confidence? No, but at some point the Afghans must take that battle themselves,” he said.

Iran's nuclear ambitions

Romney called for “very substantial covert activity” in Iran “to communicate the peril of becoming a nuclear nation.”

He said that when Obama agreed to withdraw U.S. missile defense sites from eastern Europe, “he could have exacted a price” from the Russians, namely, sanctions against Iran.

But, said Romney, “He did not.

“That was an opportunity for us to put in crippling sanctions” against Iran, he said.

He also said the U.S. should engage in aggressive covert activity and convince Iranian leaders that it “is seriously considering a military option and that we would consider using them.”

These steps, he said, would concern the Iranian people, who he said would pressure the leadership to set aside its nuclear ambitions.

Stand by Israel

Romney also said the U.S. should “stand by” Israel and not “try to negotiate for them” as he said the current administration is doing.

Obama, he said, “threw the Israelis under the bus by saying, ‘Go back to the 1967 borders.' If you disagree with your ally, you do it in private.”

But, he said, “How can you possibly have stability in a region if there continues to be an ongoing effort by the Palestinians and their allies around the world, like Iran, to obliterate the right of Israel to exist?”

Energy issues

On a key domestic issues, Romney said he believes humans are contributing to climate change “but I don't know by how much, a lot or a little. And so I'm not willing to adopt multi-trillion-dollar programs to reduce greenhouse gases in America.”

He opposes cap-and-trade and a carbon tax, and he said he will push for a domestically based energy policy, which he said “will have the byproduct of being less CO2 emitting than our current sources.”

Romney said he would focus on allowing private industry to develop domestic oil, natural gas, coal and long-term, nuclear energy. Renewables are part of the mix, he said, but he opposes “sending checks for a half-billion dollars as a venture capitalist to various favored solar companies” and said the federal government should invest only in “basic” scientific research rather than specific favored industries or companies.