Brussels — Public attention has been focused on the massive Soviet naval maneuvers taking place in the North Atlantic this week. But at NATO headquarters, concern has turned to several other Soviet military moves that will have far deeper and more long-term repercussions for Western security.
''It's a perfectly routine exercise,'' said Col. Jonathon Alford, deputy director of the London-based International Institute of Strategic Studies, commenting on the maneuvers. ''There's nothing sinister about them.''
Causing greater concern, however, were the recent disclosures that Soviet arms deliveries to less-developed countries (LDCs) have tripled since 1975 and that the number of operational Soviet SS-20 nuclear missiles will increase by nearly 10 percent in coming months.
According to a new NATO report, the value of Soviet arms deliveries to LDCs - mainly Syria, Iraq, Libya, and India - rose from $2 billion in 1975 to $5.8 billion in 1982.
''The Soviet Union hopes that the sale of arms to LDCs will put these countries in a position of long-term dependence on Moscow for spares and future supplies,'' the report said. ''Arms supplies may also enable the Russians to increase their influence in the armed forces of the countries concerned.''
The disclosure of rising military sales to the third world came just before NATO officials announced the expected deployment ''within months'' of 27 new SS- 20 medium-range nuclear missiles on three bases - one west of the Urals and two east of the mountain range - now under construction, bringing the total to 405, with a warhead capacity of 1,215. This does not include the more than 200 older SS-4 medium-range nuclear missiles the Soviet Union has deployed.
NATO officials say the buildup is consistent with oft-stated Soviet pledges to respond to the planned deployment of 572 new United States cruise and Pershing II nuclear missiles in five West European countries, which began last year.
Also riveting NATO attention has been the ''forward deployment'' of SS-12 (with a range of about 900 kilometers, or 560 miles) and SS-22 (with a similar range but greater accuracy) nuclear missile units from Soviet bases to ones in East Germany and Czechoslovakia.
''This is a very recent development,'' according to the US assistant secretary of state for European affairs, Richard R. Burt.
Soviet military sales to third-world countries, meanwhile, have risen in recent years while the Kremlin's economic aid to noncommunist developing countries has dropped significantly, according to the recently released NATO report, which put such aid at $473 million in 1975 and $382 million in 1982.
The report said that, on the other hand, Soviet-bloc economic aid to communist developing countries rose during the same period from $1.8 billion to
''The noncommunist developing countries are considered an area to be penetrated by political, trade, and military means,'' the report said, ''but they are not the target of a consistent and sustained economic aid policy.'' Western aid to the third world is five times larger, according to the report.
Moscow's ''opportunism,'' the report says, will be tempered in the future by ''objective resource constraints.''