Responding to North Korea's missile tests, congressional Republicans urged greater efforts to build a national missile defense system and proposed new sanctions on nations doing weapons business with North Korea.

"We have to have a defense that allows us to shoot down incoming ballistic missiles," said House Armed Services Committee Chairman Duncan Hunter, R-Calif., at a news conference Tuesday.

House Majority Leader John Boehner, R-Ohio, also said the North Korean test-firing last week of seven missiles including one that potentially could reach the United States underscored the need for a U.S. missile defense system.

"We and the rest of the world would feel much safer if in fact we had a missile defense system up and operating," he said.

Senate Majority Leader Bill Frist, R-Tenn., said he planned to introduce legislation that would add North Korea to a nonproliferation act that currently outlines sanctions against foreign individuals who supply weapons technology to Iran and Syria.

CountryWatch: North Korea

"North Korea's pursuit of nuclear weapons and its possession of long-range missiles that could potentially hit the U.S. is a grave threat to the security of the American people and to peace and stability in East Asia," Frist said in a statement.

The nonproliferation act, passed in 2000, originally applied only to Iran. It was expanded to include Syria in 2005.

Under the measure, the president can impose sanctions on any foreign person who transfers goods and technologies to those countries that contribute to their ability to produce missiles, nuclear weapons or weapons of mass destruction. Foreign persons who acquire such items from those countries are also subject to sanctions.

The sanctions for such people could include a ban on their obtaining U.S. government contracts or U.S. export licenses.

Hunter said he planned to confer with Senate Armed Services Committee Chairman John Warner, R-Va., about putting more money for missile defense in a defense spending bill now being negotiated between the House and Senate so the country can "move ahead with these systems as rapidly as possible."

Americans, he said "are in a race against time" in defending themselves against threats such as the North Korean Taepodong-2 missile, which failed its July 4 test but is thought to have been designed to be capable of hitting the western United States.

The Pentagon says the current system is capable of defending against a limited number of missiles in an emergency, and President Bush earlier said the United States had a "reasonable chance" of shooting down the North Korean long-range missile had it not failed.

More than $100 billion has been spent on the program since 1983, including $7.8 billion authorized for the current fiscal year.

Hunter criticized Democrats who opposed Bush's 2001 decision to withdraw from the Anti-Ballistic Missile Treaty and who have annually sought cuts in the administration's missile defense spending proposals.

In May the House defeated a Democratic-supported amendment that would have cut $4.7 billion from the $9.1 billion allotted for missile defense in the 2007 defense bill.

"It's time for the Democrats to stop fighting the ghost of Ronald Reagan," Hunter said. Reagan was an early supporter of a missile defense system, that opponents derided as "Star Wars."

But Rep. John Tierney, D-Mass., author of the amendment to cut missile defense spending, said numerous government studies have come out against building a weapons defense system that has yet to be proven reliable in test runs.

Spending billions on a system before it has been adequately tested would give Americans a false sense of security, he said. "It's too bad people are choosing to politicize this issue."

Hunter acknowledged the missile interception system is still in an "immature state."