BRUSSELS -- NATO foreign ministers on Tuesday endorsed a decision to send Patriot missile batteries to Turkey, as concerns persisted about reports of heightened activity at Syria's chemical weapons sites.
Turkey, a member of the alliance and a supporter of the Syrian opposition to President Bashar al-Assad's government, requested the batteries last month, fearing that it might be vulnerable to a Syrian missile attack, possibly with chemical weapons.
"Turkey asked for NATO's support, and we stand with Turkey in a spirit of strong solidarity," Anders Fogh Rasmussen, the secretary general of the alliance, said in Brussels. "To anyone who would want to attack Turkey, we say, 'Don't even think about it.' "
NATO said that the alliance would "augment" Turkey's air defenses with the missiles, which are effective against other missiles or aircraft. Officials emphasized that the missile deployment was defensive in nature, and not intended to establish a buffer zone in northern Syria or a no-fly zone over the country.
The missile batteries, drawn from American, German and Dutch forces, will not be operational in Turkey for several weeks, diplomats said. Each of the three nations will decide individually how many batteries to deploy in Turkey and for how long.
NATO couched the decision as a statement of its resolve. But the move reflected a minimalist vision of the alliance's role in dealing with humanitarian crises beyond its members' borders. Though Mr. Rasmussen described the fighting in Syria, which has killed an estimated 40,000 people, as "outrageous," he said that NATO's responsibility was to protect the population and territory of its members, and he emphasized that the alliance would not intervene in Syria to stop the violence.
"We have no intention to intervene militarily," he said.
Alliance members received reports from the United States and other countries on Tuesday concerning activity at Syria's chemical weapons sites, which was said to be increasing. Foreign Minister Laurent Fabius of France said the information had not been confirmed, but Mr. Rasmussen said the report nonetheless prompted "grave concerns."
The Patriot batteries in Turkey will be linked to NATO's air defense system and will be under the alliance's command and control. If a Syrian missile were to be fired at Turkey, longer-range radar systems would identify the missile's trajectory and cue the Patriot batteries to take countermeasures.
The response by the missile batteries would be nearly automatic, firing interceptor missiles to destroy the target by ramming into it, a tactic the military calls "hit to kill." At least some of the Patriot batteries will be PAC-3 versions, the most modern.
When used for antimissile defense, the Patriot batteries have a range of 16 miles; they will be placed too far from the border to fire into Syrian airspace. The missiles' warheads and any debris from collisions would fall on Turkish territory.
Russia has complained about the Turkish request for the missiles, apparently fearing that it might be a prelude to direct NATO involvement in the conflict, which the alliance has so far avoided. As it became clear that the alliance planned to proceed anyway, Russian officials tempered their criticism.
Sergey V. Lavrov, the Russian foreign minister, was at NATO headquarters on Tuesday to represent his country in the NATO-Russia Council. He asserted that Moscow had no objection to steps by the alliance to defend its members, though he still suggested that the Patriot deployments were not needed.
"We are not trying to interfere," Mr. Lavrov said at a news conference. "We are just attracting attention to the fact that threats should not be overstated."
Mr. Lavrov also played down reports of increased activity at Syria's chemical weapons sites, saying that his government had asked the Assad government about "rumors" that chemical weapons were being moved and was told they were baseless.
American and Western officials took the reports more seriously. On Monday, Mr. Rasmussen said that "Syrian stockpiles of chemical weapons are a matter of great concern."
The Netherlands has sent Patriot batteries to Turkey twice before -- in 1991, as a defense against Iraq's Scud missiles before the Persian Gulf war, and in 2003 before the United States-led invasion of Iraq.
This article originally appeared in The New York Times.