Armed men who prompted four National Guard members to pull back from an observation post at the Arizona-Mexico border probably weren't trying to test the reaction of the troops, the head of the Arizona National Guard said Monday.

They likely happened upon the soldiers while walking across rocky terrain from Arizona into Mexico, said Maj. Gen. David Rataczak, speculating that the gunmen were carrying drug money south across the border.

In the face of criticism that the troops set a bad precedent for border security, Rataczak told a homeland security committee at the Arizona Legislature that the troops acted properly in relocating to a nearby site and calling in the Border Patrol to respond.

"They did exactly what they were told to do," said Rataczak, adding that the actions of the soldiers prevented an international incident from occurring.

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The four National Guard soldiers from Tennessee were on the lookout at a post near Sasabe on Jan. 3 when they spotted four to eight gunmen who were approaching.

Arriving at the scene about 15 minutes later, the Border Patrol tracked the armed men back to the border, but weren't able to find them. No shots were fired.

Over the last three weeks, advocates for tougher immigration enforcement have questioned the point of having troops on the border if they can't confront such dangers.

Supporters of the decision to call in the Border Patrol to respond to the incident said the troops were never intended to perform law enforcement duties, but instead were there to pick support duties that tie up immigration agents, who then have more time to catch illegal immigrants.

"They are not able to do anything," said Republican state Rep. Warde Nichols of Chandler, chairman of the committee. "They have to just radio their communications. They have to take defensive postures where they can't basically fire until fired upon."

Nichols plans to file a bill this week that would put the National Guard one step closer to immigration enforcement by authorizing troops to apprehend illegal immigrants.

The four soldiers in the incident near Sasabe were among the 6,400 National Guard members sent to the four southern border states to perform support duties that tie up immigration agents, who then have more time to catch illegal immigrants.

The support duties include monitoring border points, assisting with cargo inspection and operate surveillance cameras.

The rules that Guard members work under allow the troops to use force when they believe they face an imminent threat and all other means are exhausted, state officials have said.

In the Jan. 3 incident, a gunmen carrying an automatic rifle came within 15 meters of one soldier, who had a bullet in the chamber of his firearm. Both men stared at each other for several seconds and kept their rifles pointed downward, Rataczak said.

"Had that undocumented (immigrant) pointed his weapon at our soldier, I might be testifying here today, telling you why we killed an undocumented, because he would not have survived," Rataczak said.

Republican Rep. Jerry Weiers of Glendale said the rules can put Guard members in a tough position, because the gunmen probably didn't operate under the same standards.

"My real, true, honest concern here is that we don't return fire until we have been fired upon, and by then we have probably lost a life," Weiers said.

Critics said the incident had broader border security implications because armed people know the National Guard will retreat.

Rataczak said he was pleased with the outcome and disputed that the incident was a retreat.

The four soldiers weren't overrun and didn't flee, but rather moved to a site a short distance away where they could continue to keep their eyes on the gunmen, Rataczak said.

Democratic Rep. Tom Prezelski of Tucson said he was sure that the soldiers were prepared to prevail if they had faced a more serious confrontation.

"I am a little uncomfortable with the idea that we are portraying them as helpless and having their hands tied," Prezelski said.