The move is seen as the government's first effort to stop the ethnic Albanian rebels' advance.
Government tanks rumbled into Macedonia's second-largest city Monday to fight ethnic Albanian insurgents, while NATO pledged to "starve" the rebels by cutting supply lines from neighboring Kosovo.
A spokesman for the Macedonian government, Antonio Milososki, pledged "definite action" _ a major counterattack _ saying field commanders would give the order "soon."
The appearance of heavy armor in Tetovo also seemed to be an attempt by the government to show that the army was part of efforts to prevent the monthlong guerrilla war from expanding further southward from its origins along the border with Kosovo.
The government has relied primarily on police and anti-terrorist units to fight the rebels, leading to speculation about the loyalties of the conscript army, particularly its ethnic Albanian members. The rebels have called on all ethnic Albanians in Macedonia of fighting age to join their ranks.
Fighting ebbed by mid-afternoon Monday, and only the occasional boom of government artillery lobbing shells into the foothills skirting Tetovo was heard, leaving the city of 80,000 at its quietest since late last week. Still, edgy residents continued to flee.
The rebels, who say they are fighting for greater rights for ethnic Albanians, insist their battle is not being instigated by the former Kosovo Liberation Army in Kosovo, a province of Serbia, the main Yugoslav republic.
But the latest uprising shares the aspirations of ethnic Albanians in Kosovo for self-determination, if not outright independence, potentially in a "greater" Kosovo expanded with ethnic Albanian parts of Macedonia and southern Serbia.
Although ethnic relations in Slav-dominated Macedonia have been relatively trouble-free _ an ethnic Albanian party is a partner in the government _ substantial numbers of the minority feel they are treated as second-class citizens.
U.N. Secretary-General Kofi Annan condemned the escalating violence by Albanian extremists, saying it poses "a threat to stability and security in the entire region."
Annan is encouraged by the efforts of the Macedonian government "to stabilize the situation and to isolate the extremist armed groups," deputy spokesman Manoel de Almeida e Silva said at U.N. headquarters in New York.
European Union foreign ministers meeting in Belgium agreed on measures for Macedonia that included technical aid for a census _ one of the demands by the rebels, who say the number of ethnic Albanians is underreported.
Four government tanks were initially sent to Tetovo. Later Monday, one more tank, eight armored personnel carriers and eight army trucks were seen entering the city.
As the army boosted its presence, NATO Secretary-General Lord Robertson said the international force in Kosovo was moving more troops to the border with Macedonia to cut off the supply lines to insurgents.
Key demands made by Macedonia's ethnic Albanian insurgents, to the Albanian language service of Germany's Deutsche Welle earlier this month:
Changes in the Macedonian constitution to declare the country "a state of two constituent peoples, Macedonian and Albanian."
End of alleged discrimination against ethnic Albanians in political institutions.
The release "of all political prisoners," presumably a reference to six suspects in custody while facing trials for terrorism in connection with a series of bombings in 1999.
The implementation of "neutral international mediation" to resolve differences between Macedonia's Albanian minority and the Slavic majority.
The carrying out of a census by international organizations to determine the size of the ethnic Albanian community.