The Soviet Union and Vietnam signed a treaty of friendship and cooperation last night, binding the two nations more closely together against their bitter adversary in Peking.

Coinciding with reports of increased armed clashes along the Sino-Vietnamese border, the pact was described by Soviet President Leonid Brezhnev as holding "special significance" because of alleged Chinese military pressure on Vietnam.

The Kremlin signing ceremony was televised, showing Brezhnev, Premier Alexei Kosygin, Vietnamese Communist Party leader Le Duan and Premier Pham Van Dong embracing, smiling and drinking champagne toasts.

Brezhnev said in a later dinner toast that it was "predictable that [the pact] will be resented by those who do not like friendship between" Moscow and Hanoi.

But, he added, "the treaty has already become a political reality and whether they want it or not they will have to reckon with this reality."

Neither the treaty nor a joint Soviet-Vietnamese communique have yet been made public, precluding any assessments as to the degree of assistance the Russians have promised. But, according to Western intelligence sources, a Soviet airlift supporting the Vietnamese military efforts is currently under way.

The treaty culminated two days of talks and was signed by the four leaders.

Tha Hanoi-Moscow treaty also comes at a time of intensifying strife between the Soviet Union and China, mirrored in the escalating warfare between their allies, Vietnam and Cambodia. Yesterday, Hanoi again charged border incursions by the Chinese and reported sharp clashes. There are reports from Cambodia a Peking alley, that Vietnamese units have penetrated deep in Cambodia (Kampuchea) and an offensive aimed at toppling the Phnom Peah regime of Pol Pot has been predicted at the onset of the dry season next month.

At the dinner honoring the Vietnamese, Brezhnev declared the treaty "holds special significance at this complicated moment when the policy of the Chinese leadership has created new, major difficulties for socialist construction on Vietnames soil."

The accord, the first ever between the two nations, is in part a Kremlin retort to the new Peking diplomatic campaign that brought Chinese leader Hua Kuo-feng to Romania and Yugoslavia in August, alarming the Soviets and further embittering them in their long struggle with the Chinese for ideological supremacy of the Communist world.

The Soviet press has been filled with denunciations of these Peking initiatives, sharpened by the signing of a Chinese-Japanese peace treaty which Moscow sought to black and has since further denounced.

The Kremlin alarm has been deepened by steadily improving relations between Peking and Washington, as well as readiness by European nations, such as France and Britain, to sell arms to the Chinese. Just last week, top Soviet diplomatic sources warned of unspecified reprisals against Western nations that sell arms to Peking.

TTS NEWS - Underwood

The Soviet Union and Vietnam yesterday also signed economic and technical agreements that will mean millions of additional rubles of aid to Hanoi. The Russians specifically agreed to help improve vital strategic railroads linking Hanoi and the port of Haiphong and Hanoi and Ho Chi Minh City (formerly Saigon).

Vietnam has moved steadily into full alignment with Russia in the past year. This June, Vietnam was granted full membership in the Soviet bloc economic group, Comecon.

In his remarks, Brezhnev called the treaty "a document of great historic importance in the full sense of the term." He said it assured that the two countries will "grow stronger in politics, economics and other spheres of social life."

Le Duan, the Vietnamese party chief, was quoted by Tass, the official Soviet press agency, as declaring that Peking "is establishing a new alliance with imperialism and fascist hangers-on, an alliance against the socialist system and the movement of national independence." He said Peking and other reactionary nations are "pursuing a fiercely hostile policy against Vietnam."

Some diplomatic sources here had expected the two to sign a treaty of "peace and friendship," which binds more strongly. The visit of the vietnamese has been marked by several unusual signs. The first day of talks was described as having been held in an atmosphere of sincerity, comradely frankness and mutual respect." The term "frankness" is normally used here to suggest some disagreement, a circumstance seemingly at variance with the present close ties between Hanoi and Moscow.

The Soviets have signed similar treaties with Warsaw Pact nations as well as Angola, Mozambique, Ethiopia, Finland and Iraq. Such traties are accorded considerable significance here, intensifying the relationship between Moscow and the signatories. In this decade, Egypt and Somalia have signed and then abrogated such treaties with the Soviets.