But, in the end, they may well sit idly by if North Korea follows through with a planned rocket launch in the coming days.
Despite a decade of preparations since the North's last major launch in 1998, Tokyo
- the most anxious of North Korea's neighbors - would be hard-pressed to make good on its threat to shoot down anything that poses a danger to its islands.
After initially hinting it might try to shoot down any rocket, Japan's leaders have recalibrated their rhetoric.
On Friday, Japan's defense minister gave the order to shoot down any debris from the launch if it is deemed a threat to Japanese territory. The order mobilized PAC-3 Patriot missiles to the coast and AEGIS-equipped warships to the Sea of Japan.
But short of such a threat to Japanese territory, Japan has not said it would intercept the launch
- a move that North Korea has warned would be an act of war.
Shooting down fragments, meanwhile, presents a technical challenge that Japan's leaders acknowledge they may not be up to.
"Our country has never done this before," Foreign Minister Hirofumi Nakasone said this week. "And we don't know how or where it may come flying."
Posturing aside, Tokyo sees the likelihood of danger as low.
"It is unlikely under normal conditions that any debris would fall on Japan," said Chief Cabinet spokesman Takeo Kawamura. "We urge our people to remain calm."
Japan successfully tested intercepting a medium-range missile last year, but it has also failed once in the past. The country has never tested its capability to intercept a long-range rocket such as the one now on North Korea's launch pad.
The North has further complicated matters with its claim that it is launching a satellite and has the right to develop a peaceful space program.
A 2006 U.N. Security Council resolution prohibits North Korea from engaging in ballistic activity, which Washington and its allies say includes using a rocket to send a satellite into space. The rockets used in satellite launches can be modified for missile use, and the data from a satellite launch can be applied to improve missile technology.
But by saying it is launching a satellite - not testing its latest missile capabilities
- the North has given itself a good deal of wiggle room.
No country has ever shot another country's satellite launch, and never before has a satellite been shot out of orbit, except in test exercises involving satellites and interceptors of the same nation.
"If it's a satellite, no one would want to intercept it," said Lance Gatling, an independent missile analyst. "It's like intercepting a peaceful departing aircraft."
Gatling said it is fairly easy to distinguish if a launch is intended to place a satellite in orbit.
"A satellite is not aimed at Japan," he said. "It would go over Japan and into space. So you can tell from a variety of angles."
That should be determined quite quickly after the North's launch.
Over the past several years, the U.S. has upgraded a major tracking operation at Misawa Air Base in northern Japan. If U.S. military satellites detect a flash of heat from a missile launch in North Korea, within a minute computers at the base can plot a rough trajectory and share that information with Japan.