DEFENSE : Myanmar Gears Up for Offensive : Ethnic groups are target. New weapons strengthen military’s hand.

After a two-year shopping spree for sophisticated arms from China, Poland and Yugoslavia, Myanmar’s military is gearing up for a major offensive against ethnic insurgents based along the border with Thailand, according to Western diplomats.

The military in Myanmar, formerly called Burma, is building roads, improving logistics and moving up ammunition in preparation for the offensive, which will begin in the dry season that starts late this month.

Another sign of preparations for the offensive, according to the diplomats, is the appearance of military press gangs rounding up civilians to work as porters supplying government troops in the border region. Hundreds of porters have died of disease and abuse in the last couple of years under the harsh conditions prevailing in the jungle at the border.

In April, the military junta, called the State Law and Order Restoration Council, announced that it would observe a unilateral cease-fire with Karen and Kachin rebel groups that have been battling for autonomy virtually since independence was granted by Britain in 1948.

The military government reportedly followed up its cease-fire with a secret approach to the rebels for negotiations, using Thai military officers as intermediaries. But the Karen and Kachin groups not only rejected the offer, they used the summertime lull to launch new attacks against the junta, capturing government outposts near Shwegyin and Timukha in the area near the Thai border.

“They are not stopping fighting,” complained U Aye, director general of Myanmar’s Foreign Ministry. “They are not only returning fire, but they are trying to go on the offensive.”

Last year, government forces came dramatically close to overrunning the main rebel base at Mannerplaw but were turned back at the last minute after heavy losses on both sides. Western diplomats here in Yangon, the capital, expect this year’s offensive to be even stronger.

The government’s hand will be strengthened in part by a massive arms acquisition program that has proceeded despite the opposition of the United States and European countries, which have imposed an arms embargo on Myanmar because of human rights abuses.

According to a longtime resident of Yangon, the military has acquired more than $600 million worth of arms in the last couple of years, with more on order. The major suppliers have been China, Poland and Yugoslavia.

In order to pay for the arms, Myanmar spent more than half of its financial reserves, drawing down the treasury by $300 million in 1991 alone.

“These arms are for our legitimate defense needs,” U Aye said. “There hasn’t been an excessive amount of buying, just what’s adequate for our needs.”

The Chinese alone have sold $500 million worth of arms to Yangon, including $150 million in cash orders and $350 million in barter trade.

Myanmar has received Hainan-class gunboats, F-7 attack aircraft and 60 T-63 tanks from Beijing, according to the resident, who closely monitors military deals in Yangon. The country also received artillery and submachine guns.

Perhaps the greatest uproar in the West recently has been caused by the sale of 20 MI-2 Hoplite attack helicopters from Poland. The deal reportedly amounted to $50 million.

As one diplomat noted angrily, Polish President Lech Walesa sent an envoy to Myanmar to express concern about imprisoned democracy advocate Aung San Suu Kyi at the same time the helicopters were being uncrated for action against Myanmar’s ethnic rebels.

In addition to the Hoplite aircraft, Poland has sold Myanmar a dozen conventional helicopter transports, as well as mortars and ammunition.

Maj. Gen. Thein Win, chief of the Myanmar air force, was in Poland in August negotiating for the sale of Polish jet fighter training aircraft, according to the resident of Yangon.

After Poland, Myanmar’s next largest supplier of arms is what remains of Yugoslavia, which sold Yangon six Galeb-4 jets, light attack warplanes. The warplanes, equipped with rocket pods and cannons, cost between $30 million and $40 million.

Singapore also has been a major arms supplier, with two private arms firms selling mainly spare parts and ammunition. South Korea, Israel, Portugal and Spain also have sold a variety of arms to the Myanmar government, according to the longtime resident.

Myanmar has an army of 210,000 men, more than its former colonial masters in Britain. With the arms purchases, Myanmar’s armed forces have “gone from a fourth-class army to a second-class army,” the resident said.

The purchase of so many fighter aircraft remains a mystery because the aircraft are designed to be used against other aircraft and cannot easily be used against the rebels or for crushing internal dissent.

But the resident of Yangon commented, “The fighters are what we call ‘toys for the boys’ “--meaning a reward for Myanmar’s air force.