Ryan, who is mentioned frequently as a potential presidential candidate, said defense should be the federal government's top priority and any further cuts in military spending would put the U.S. at a disadvantage in foreign affairs.
"I really think that what that does is it sends the wrong signals to the world," Ryan said during a packed town hall-style meeting in North Prairie, a community of about 2,100 southwest of Milwaukee. "It sends signals to the Chinese that our military is shrinking and therefore they have an incentive to catch up to us."
It was the first in a four-day series of such meetings for Ryan, and at an event later Tuesday in Franklin, people began lining up an hour early to get inside. Security was tight with more than a half-dozen police officers at both events, a ban on backpacks and residents turned away when the rooms reached capacity.
The Janesville Republican said U.S. defense policy cannot be blamed for Russia's recent move into Crimea. But he said it did not help matters for the U.S. to look weak.
"Russia is responsible for taking over Crimea, that's where the blame should be," Ryan said. "But I think it's a reminder that it's a much more dangerous world. These are not peaceful times ... we should not give signals that we are going to withdraw and retreat."
Ryan, 44, also advocated more oil and gas drilling on federal land, saying greater production at home would help the U.S. economy and increase national security by reducing reliance on oil from the Middle East. Domestic oil production has increased dramatically in recent years and as of October, the U.S. was producing more oil than it imported. Ryan said increasing natural gas production would allow the U.S. to export the fuel to European nations that now rely on Russia.
He opened both town hall meetings with a presentation on the federal budget and national debt. He reiterated his call to curb federal spending, saying the nation's debt could grow to nearly twice the annual U.S. economy if nothing was done. Asked if he would support a balanced budget amendment, Ryan said he favors a balanced budget when there are spending caps - he would not want to raise taxes to cover more spending.
Ryan also advocated a "simpler" tax code with fewer deductions and tax brackets.
He criticized what he described as the high cost and ineffectiveness of the federal health care overhaul, saying he expected Republicans to introduce legislation this year to change it. He said he favors creating a government-backed "high-risk" insurance pool for people with pre-existing conditions because that would lower rates for others.
"We're going to be moving reforms along these lines to say here's a better way of doing health care," he said.
Ryan spoke to mostly friendly crowds but faced several questions in Franklin from immigration reform advocates who arrived on a bus being used for a national immigration rights tour. One expressed her disappointment that immigration reform legislation hadn't yet been brought up for a vote in the House. Another asked Ryan why funding hadn't been made available to support President Barack Obama's executive order granting amnesty to children brought to the U.S. illegally by their parents.
Ryan said many in Congress feel that Obama has exceeded his authority with executive orders and are reluctant to fund them. But he supports a path to citizenship for those children, many who are now adults.
Ryan also addressed trade talks in which the European Union wants to bar U.S. cheese-makers from using European place names for their cheese.
"To suggest that we are going to engage in a trade agreement that suggests that our cheese-makers can't call havarti 'Havarti' or gouda 'Gouda' is ridiculous," he said.