President Carter's airlift -- and slower sealift -- of $3.5 million worth of arms to Thailand are being called "obviously too little, but possibly not too late" by specialists on Southeast Asia here.
Small arms, artillery, ammunition, and an improved model of the old US Patton tank are being sent to the Thais following the attack last week by Vietnamese troops against Cambodian refugees in Thailand and against Thai villages.
The immediate airlift to Bangkok, the Thai capital, by six or seven Air Force C-141 cargo planes -- at a cost of $1 million -- and the much longer sea voyage for the tanks responds to Thailand's recent urgent requests under its 1954 defense agreement with the US, Carter administration spokesmen said.
"The shipments may help to bolster Thai morale, and perhaps even symbolically warn the Soviets that we don't like their encouragement of Vietnamese adventures in Thailand," said one senior military analyst.
"What they certainly won't do is protect Thailand against any major attack or invasion. The arms and ammunition will be put to use immediately. But the tanks will get there far too late to be of any help in the immediate future."
Under the US foreign military sale program, Thailand was granted $40 million in credits for fiscal 1980, with current deliveries running to about $45 million. The fiscal 1981 request was for $50 million.
Thailand's scrappy 216,000-man armed forces (including a land army of 145,000 and an air force whose most advanced planes are about 30 Northrop F-5 fighter and ground-attack aircraft) are mainly US-supplied. But they also have some British-made equipment, including armored vehicles.
Although Vietnamese troops were not reported operating inside Thailand as President Carter announced the emergency package July 1, a State Department spokeman said "There are significant numbers of Vietnamese troops moving in Cambodian near the border."
The spokesman, John Trattner, said the airlift would carry 18 105-mm. howitzers; 38 106-mm. recoilless rifles, and about 1,000 M-16 automatic rifles.
The White House announcement said the US also would expedite "surface shipments to Thailand of small arms, artillery, and munitions. It is also arranging "to accelerate the delivery by sea of 35 improved Patton M-48-A5 tanks."
That delivery, however, cannot be completed under US law until the required 30-day congressional review period ends July 23. President Carter did not invoke his power to waive the congressional review requirement for the tanks, although this could have speeded up their delivery.
Administration analysts privately expressed concern over probable Soviet encouragement to the Vietnamese forces, which include at least one complete infantry division that operated across the border during the attacks inside Thailand. Intelligence sources say the Vietnamese have reinforced their artillery positions just behind the border with late-model Soviet cannon and short-range rocket launchers.
Soviet reconnaissance aircraft have been operating regularly from Vietnamese bases at Cam Ranh Bay and Da Nang, but US analysts have not reported any Soviet-piloted reconnaissance aircraft over the Thai border areas since the Vietnamese push began earlier this month.
In all, the Vietnamese have deployed about 120,000 troops in Cambodia and another 40,000 or so in neighboring Laos.
Thai and Us intelligence are replacing American equipment of the former South Vietnamese forces with newer Soviet materiel. Refurbished US vehicles, small arms, and artillery captured in the Vietnam war before 1973 have been used extensively by the Vietnamese.
Thai officials recently told American military experts that they believe the Vietnamese have begun to use sophisticated Soviet listening devices and other electronic warfare equipment both to facilitate their operations against the Thai Army and to spy upon the refugee camps of Cambodians located near the border, many of which have been disrupted by the recent fighting.