Nhu+ dda~ co' nha('c dde^'n tru+o+'c dda^y, ca'c chie^'n di.ch xa^m la(ng to lo+'n cu?a Ba('c Vie^.t dda~ ddu+o+.c kho+?i dda^`u va`o khoa?ng cuo^'i na(m 1964. Sang dde^'n na(m 1965, ngoa`i ca'c tra^.n dda'nh du+~ do^.i tu+` Be^'n Ha?i dde^'n Ca` Mau, Co^.ng qua^n la.i co`n gia ta(ng mu+'c ddo^. khu?ng bo^', ba('t bo+' va` gie^'t ha.i da^n la`nh o+? kha('p mo.i no+i. Qua^n DDo^.i VNCH cho^'ng tra? ma~nh lie^.t va` dda~ la`m cho lu+.c lu+o+.ng Co^.ng Sa?n o+? mie^`n Nam bi. to^?n tha^'t ghe^ go+'m tre^n phu+o+ng die^.n qua^n su+.. Vi` ma^'t nie^`m tin o+? ca'c ca'n binh Vie^.t Co^.ng mie^`n Nam, cha'nh phu? Ha` No^.i lie^`n bi' ma^.t ddu+a the^m ha`ng chu.c nga`n bo^. ddo^.i Ba('c Vie^.t va`o Nam dde^? xu'c tie^'n co^ng cuo^.c xa^m la(ng ma'u lu+?a. Ngoa`i ddo^`ng minh Hoa Ky`, mie^`n Nam Vie^.t Nam cu~ng dda~ ddu+o+.c mo^.t so^' dde^. tam quo^'c gia kha'c giu'p ddo+~ i't-nhie^`u trong vie^.c nga(n cha^.n la`n so'ng Co^.ng ddo? lan tra`n tu+` phu+o+ng Ba('c.

Ngoa`i Hoa Ky`, co' ta^'t ca? la` 34 quo^'c gia ddo^`ng minh kha'c dda~ gia'n tie^'p giu'p ddo+~ cha'nh phu? Vie^.t Nam Co^.ng Ho`a (VNCH) trong cuo^.c chie^'n cho^'ng Co^.ng Sa?n. DDo' la` ca'c quo^'c gia A' Ca(n DDi`nh (Agentina), Bi? (Belgium), Ba Ta^y (Brazil), Gia Na~ DDa.i (Canada), Co^.ng Ho`a Lie^n Bang DDu+'c (West Germany), Pha'p (France), Hy La.p (Greece), Guatamela (mo^.t quo^'c gia ta.i Nam My~, Honduras (mo^.t quo^'c gia ta.i Nam My~), Iran (Ba Tu+), A'i Nhi~ Lan (Ireland), Do Tha'i (Israel), Y' DDa.i Lo+.i (Italy), Nha^.t Ba?n (Japan), La`o (Laos), Liberia, Lu.c Xa^m Ba?o (Luxemburg), Ma~ Lai (Malaysia), Ma Ro^'c (Morocco), Ho`a Lan (Netherland hoa(.c Holland), Na Uy (Norway), Ho^`i Quo^'c (Pakistan), Nam Phi (South Africa), Tay Ban Nha (Spain), Thu.y DDie^?n (DDan Ma.ch), Tunisi, Tho^? Nhi~ Ky` (Turkey), Anh Quo^'c (England), Uruguay (mo^.t quo^'c gia ta.i Nam My~), va` Venezuala (mo^.t quo^'c gia ta.i Nam My~). Trong so^' nhu+~ng quo^'c gia na`y, chi? co' U'c, Ta^n Ta^y Lan, Tha'i Lan, va` DDa.i Ha`n dda~ gu+?i qua^n sang Vie^.t Nam dde^? chie^'n dda^'u. Nhu+~ng nu+o+'c kha'c chi? giu'p ddo+~ ve^` ca'c phu+o+ng die^.n da^n su+. nhu+ y te^', canh no^ng, co^' va^'n ky~ thua^.t, v.v.

Tha'ng 2 na(m 1965, ddo+n vi. dda^`u tie^n cu?a Nam Trie^`u Tie^n (DDa.i Ha`n) dde^'n Vie^.t Nam. DDo' la` mo^.t tie^?u ddoa`n Co^ng Binh va` mo^.t tie^?u ddoa`n Bo^. Binh dde^? ye^?m tro+.. Ca'c ddo+n vi. na`y ddo'ng o+? Bie^n Ho`a. Nhie^.m vu. dda^`u tie^n cu?a ho. la` xa^y mo^.t xa lo^. bao quanh Saigon dde^? gia?i to?a na.n ke.t xe trong va` ngoa`i tha`nh pho^'. Mo^~i khi qua^n ddo^.i vo+'i qua^n so^' tha^.t nhie^`u ca^`n pha?i di chuye^?n, ca'c ddoa`n qua^n xa (military vehicles) co' the^? xu+? du.ng xa lo^. na`y va` se~ kho^ng la`m ta('t nghe~n va^'n dde^` lu+u tho^ng trong thu? ddo^ Saigon. Ro^`i dde^'n mu`a Thu na(m 1964, ddo+n vi. chie^'n dda^'u dda^`u tie^n cu?a Nam Trie^`u Tie^n dde^'n Vie^.t Nam. Ta^'t ca? binh si~ DDa.i Ha`n dde^`u la` nhu+~ng thanh nie^n ti`nh nguye^.n, vi` lo+`i ke^u go.i cu?a quo^'c gia, va` cu~ng vi` ly' tu+o+?ng tu+. do va` cho^'ng Co^.ng. Vi` dda^'t nu+o+'c ho. dda~ tu+`ng mo^.t la^`n tra?i qua chinh chie^'n vo+'i Co^.ng Sa?n Ba('c Trie^`u Tie^n ne^n ca'c binh si~ na`y dda~ mang dde^'n Vie^.t Nam mo^.t tinh tha^`n cho^'ng Co^.ng ra^'t sa('c be'n.

Su+ ddoa`n Ma~nh Ho^? va` Ba.ch Ma~ dde^`u la` hai su+ ddoa`n thie^.n chie^'n cu?a qua^n ddo^.i Nam Trie^`u Tie^n. Ta^'t ca? ca'c binh si~, tu+` binh nha^'t, si~ quan, le^n dde^'n ha`ng tu+o+'ng la~nh dde^`u thu+o+`ng xuye^n re`n luye^.n Tha'i Cu+.c DDa.o dde^? tha^n the^? cu+o+`ng tra'ng va` dda^`u o'c tra'ng kie^.n. Ngoa`i vie^.c luye^.n vo~, qua^n ddo^.i Nam Trie^`u Tie^n cu~ng co' mo+? ca'c lo+'p Tha'i Cu+.c DDa.o dde^? da.y vo~ cho ca'c thanh nie^n Vie^.t Nam dde^? mo+? ro^.ng khuo^n kho^? hoa.t ddo^.ng trong la~nh vu+.c da^n su+. vu.. Ca'c ddo+n vi. Nam Trie^`u Tie^n ddo'ng qua^n ta.i ti?nh Bi`nh DDi.nh thuo^.c Vu`ng 2 Chie^'n Thua^.t. Nhie^.m vu. cu?a ho. la` giu+~ an ninh tre^n Quo^'c Lo^. 1. Na(m 1967, lu+.c lu+o+.ng Nam Trie^`u Tie^n mo+? hai chie^'n di.ch ha`nh qua^n to lo+'n trong vu`ng Bi`nh DDi.nh va` dda~ tie^u die^.t ho+n 1,500 Vie^.t Co^.ng.

Ngoa`i Nam Trie^`u Tie^n, Tha'i Lan la` quo^'c gia thu+' nhi` o+? vu`ng DDo^ng Nam A' dda~ gu+?i qua^n ddo^.i sang Vie^.t Nam chie^'n dda^'u. La` mo^.t vu+o+ng quo^'c to lo+'n vo+'i ddi.a the^' chie^'n lu+o+.c qua^n tro.ng na(`m ke^` ca^.n Vie^.t Nam, La`o, va` Cam Bo^'t, Tha'i Lan dda~ ddu+o+.c Hoa Ky` xem nhu+ la` mo^.t trong nhu+~ng ca'c quo^'c gia quan tro.ng nha^'t ta.i A' Cha^u. Lu+.c lu+o+.ng chie^'n dda^'u dda^`u tie^n cu?a Tha'i lan sang Vie^.t Nam va`o na(m 1967. DDo' la` mo^.t su+ ddoa`n Bo^. Binh mang te^n Ha('c Ba'o. Ta^'t ca? ca'c binh si~ thuo^.c su+ ddoa`n na`y dde^`u la` chi' nguye^.n qua^n, trong ddo' co' ca? ngu+o+`i con trai cu?a vi. ddu+o+ng kim Thu? Tu+o+'ng. Lu+.c lu+o+.ng Tha'i ddo'ng qua^n ta.i Vie^.t Nam ddu+o+.c va`i na(m. Va` trong nhu+~ng na(m ddo', qua^n so^' cu?a ho. go^`m khoa?ng 11 nga`n ngu+o+`i. Qua^n ddo^.i Tha'i hoa.t ddo^.ng chung vo+'i Su+ DDoa`n 9 Bo^. Binh Hoa Ky`. Ho. ddo'ng qua^n ga^`n Sa`i Go`n va` ddu+o+.c trao nhie^.m vu. giu+~ gi`n an ninh cho ti?nh Bie^n Ho`a.

Ne^'u dda~ nha('c dde^'n Nam Trie^`u Tie^n va` Tha'i Lan thi` kho^ng the^? no'i dde^'n su+. ddo'ng go'p cao quy' cu?a U'c DDa.i Lo+.i va` Ta^n Ta^y Lan. Tre^n ba?n ddo^` ddi.a ly' quo^'c te^', ca? hai quo^'c gia na`y dde^`u ddu+o+.c lie^.t ke^ thuo^.c vu`ng Cha^u A'. Nhu+ng nhu+~ng ngu+o+`i U'c va` ngu+o+`i Ta^n Ta^y Lan dde^`u la` nhu+~ng ngu+o+`i da tra('ng, to'c va`ng, va` ma('t xanh. Ca? hai quo^'c gia na`y dde^`u ddu+a qua^n dde^'n Vie^.t Nam va`o khoa?ng giu+~a na(m 1965. Va` ma(.c da^`u vo+'i qua^n so^' nho? nhoi, nhu+ng qua^n ddo^.i U'c va` cu~ng dda~ to? ra ra^'t thie^.n chie^'n. Ho. ra^'t gio?i ve^` chie^'n thua^.t ha`nh qua^n le? te? trong ru+`ng dde^? truy lu`ng Vie^.t Co^.ng. Qua^n ddo^.i U'c ddo'ng qua^n o+? ti?nh Phu+o+'c Tuy, do.c theo vu`ng duye^n ha?i, va` ho. co' nhie^.m vu. giu+~ an ninh cho mo^.t pha^`n cu?a ti?nh na`y do.c theo Quo^'c Lo^. 15 tu+` Bie^n Ho`a ra Vu~ng Ta`u. Kha? na(ng chie^'n dda^'u cu?a ca'c binh si~ U'c va` Ta^n Ta^y Lan ra^'t cao. Va` ho. dda~ la`m cho DDa.i Tu+o+'ng William Westmoreland, To^?ng Tu+ Le^.nh Lu+.c Lu+o+.ng Hoa Ky` ta.i Vie^.t Nam, he^'t lo`ng khen ngo+.i. Trong quye^?n ho^`i ky' A Soldier's Report (Ba?n Tu+o+`ng Tri`nh Cu?a Mo^.t Ngu+o+`i Li'nh) xua^'t ba?n va`o dda^`u tha^.p nie^n 1990, Tu+o+'ng Westmoreland vie^'t nhu+ sau:

""Mu`a he` na(m 1966, qua^n U'c ddu.ng tra^.n lo+'n vo+'i ddi.ch. Lu'c a^'y mo^.t dda.i ddo^.i ddang lu.c soa't trong ru+`ng cao su thi` cha.m tra'n vo+'i mo^.t lu+.c lu+o+.ng ddi.ch u+o+'c chu+`ng mo^.t nga`n ru+o+~i. Trong ba tie^'ng ddo^`ng ho^`, du+o+'i co+n mu+a ta^`m ta~ ne^n kho^ng the^? nho+` dde^'n phi co+ ye^?m tro+., dda.i ddo^.i U'c khoa?ng mo^.t tra(m binh si~ chie^'n dda^'u anh du~ng cho^'ng tra? cuo^.c ta^'n co^ng bie^?n ngu+o+`i cu?a ddi.ch. Lu'c be^n qua^n U'c ga^`n ca.n he^'t dda.n du+o+.c, tru+.c tha(ng U'c ba^'t cha^'p dda.n ddi.ch ba('n le^n dda~ nha`o xuo^'ng tie^'p te^' the^m dda.n. Ra^'t may, nho+` mu+a lo+'n va` tie^'ng su'ng re^`n vang ne^n hai dda.i ddo^.i thie^'t gia'p tie^'n sa't dde^'n be^n ho^ng ma` ddi.ch kho^ng pha't gia'c ki.p. Bi. pha?n co^ng ma~nh lie^.t, ddi.ch buo^.c lo`ng pha?i tha'o cha.y, bo? la.i 265 xa'c. Be^n U'c bi. thie^.t ma^'t 17 binh si~. Trong so^' na`y co' sa'u ngu+o+`i bi. gu.c nga~ ngay trong loa.t dda.n dda^`u cuo^.c giao tranh."

Ve^` phi'a qua^n ddo^.i Ta^n Ta^y Lan, ho. chuye^n mo^n va` ra^'t gio?i ve^` pha'o binh. Ha^`u he^'t ca'c cuo^.c ha`nh qua^n cu?a lu+.c lu+o+.ng U'c dde^`u ddu+o+.c qua^n ddo^.i Ta^n Ta^y Lan ye^?m tro+. he^'t mi`nh. Ca? hai lu+.c lu+o+.ng na`y thu+o+`ng hay pho^'i ho+.p ra^'t cha(.t che?. Va` cu~ng theo su+. nha^.n xe't cu?a Tu+o+'ng William Westmoreland, kha? na(ng chie^'n dda^'u cu?a ca'c binh si~ Ta^n Ta^y Lan cu~ng ngang ba(`ng vo+'i cu?a lu+.c lu+o+.ng U'c.

Nhu+ dda~ nha('c dde^'n o+? pha^`n tre^n, Hoa Ky`, Ta^n Ta^y Lan, U'c DDa.i Lo+.i, Nam Trie^`u Tie^n, va` Tha'i Lan la` na(m quo^'c gia gu+?i binh si~ sang Vie^.t Nam chie^'n dda^'u. Ca'c quo^'c gia kha'c tuy kho^ng giu'p ddo+~ ve^` ma(.t qua^n su+., nhu+ng ho. cu~ng dda~ cho Vie^.t Nam Co^.ng Ho`a mo^.t nie^`m khi'ch le^. lo+'n lao qua nhu+~ng pha^`n vie^.n tro+. da^n su+., ky~ thua^.t, hoa(.c co^' va^'n. Nhu+ Phi Lua^.t Ta^n va` DDa`i Loan la` hai quo^'c gia dda~ nhie^.t ti`nh trong vie^.c tro+. giu'p Vie^.t Nam Co^.ng Ho`a trong co^ng cuo^.c kie^'n thie^'t dda^'t nu+o+'c. DDa`i Loan gu+?i va`i pha'i ddoa`n sang Vie^.t Nam dde^? giu'p ve^` ma(.t co^' va^'n ky~ thua^.t. Co`n Phi Lua^.t Ta^n thi` co' 2,000 ngu+o+`i ti`nh nguye^.n sang Vie^.t Nam dde^? tro+. giu'p ve^` ma(.t da^n su+. y te^'. DDa(.c bie^.t trong khoa?ng tho+`i gian o+? ta.i Vie^.t Nam, chi'nh ca'c ngu+o+`i Phi dda~ thie^'t la^.p nhie^`u la`ng ddi.nh cu+ o+? ti?nh Ta^y Ninh dde^? cu+'u giu'p ha`ng chu.c nga`n ngu+o+`i da^n ti. na.n Co^.ng Sa?n co' no+i ta.m tru'.

-	Kho^ng Qua^n Hoa Ky` bay ta^'t ca? 148,000 phi vu. (do^.i bom, oanh ta.c, tha'm thi'nh, v.v.) ta.i chie^'n tru+o+`ng Ba('c Vie^.t (Phillip Davison: Vietnam At War, tr.394).
-	Trong na(m na`y, 15 trung ddoa`n Co^.ng Sa?n Ba('c Vie^.t (khoa?ng 58,000 bo^. ddo^.i) ddu+o+.c bi' ma^.t thuye^n chuye^?n va`o mie^`n Nam Vie^.t Nam. (Phillip Davison: Vietnam At War, tr.395).
-	To^?ng so^' lu+.c lu+o+.ng chie^'n dda^'u cu?a Co^.ng qua^n (Vie^.t Co^.ng mie^`n Nam va` Co^.ng Sa?n mie^`n Ba('c) co' ma(.t ta.i chie^'n tru+o+`ng mie^`n Nam ddu+o+.c u+o+'c lu+o+.ng va`o khoa?ng 282,000 ngu+o+`i. (Phillip Davison: Vietnam At War, tr.395).
-	Ti'nh dde^'n cuo^'i na(m, lu+.c lu+o+.ng Hoa Ky` ta.i Vie^.t Nam le^n dde^'n 385,000 ngu+o+`i, go^`m 5 su+ ddoa`n Bo^. Binh, 2 su+ ddoa`n Thu?y Qua^n Lu.c Chie^'n, co^.ng the^m qua^n so^' cu?a Kho^ng Qua^n, Ha?i Qua^n, va` cu`ng nhie^`u lu+.c lu+o+.ng ye^?m tro+. kha'c. (Phillip Davison: Vietnam At War, tr.395).
Tha'ng 1	Su+ DDoa`n 1 Kho^ng Ky. Hoa Ky` mo+? cuo^.c ha`nh qua^n MASHER (sau ddo^?i te^n la.i tha`nh WHITEWING) o+? ti?nh Bi`nh DDi.nh. Cuo^.c ha`nh qua^n ke'o da`i 6 tua^`n le^~. Co^.ng qua^n bi. thie^.t ha.i na(.ng vo+'i 1,324 che^'t va` 633 te^n bi. ba('t la`m tu` binh. (Phillip Davison: Vietnam At War, tr.404).
Tha'ng 2	Hai Su+ DDoa`n 324B va` 341 CSBV xa^m nha^.p va`o la~nh tho^? Vie^.t Nam Co^.ng Ho`a qua ca'c nga~ bi' ma^.t o+? ga^`n vu`ng phi qua^n su+.. Cu~ng trong tha'ng na`y, mo^.t su+ ddoa`n CSBV kha'c ddo'ng ta.i La`o dda~ xa^m nha^.p va`o ti?nh Thu+`a Thie^n cu?a Nam Vie^.t Nam. Phillip Davison: Vietnam At War, tr.417).
Tha'ng 2-3	Cha'nh phu? Hoa Ky` la^`n dda^`u tie^n "ba^.t dde`n xanh" cho phe'p ma'y bay Kho^ng Qua^n va` Ha?i Qua^n do^.i bom ca'c kho da^`u xa(ng cu?a Ba('c Vie^.t. Lon O. Nordeen: Air Warfare In The Missile Age, tr.20).
Tha'ng 4	Ga(.p tho+`i tie^'t to^'t dde.p, ca'c phi co+ tu+` Ha`ng Kho^ng Ma^~u Ha.m USS Kitty Hawk va` Ticonderoga bay nhie^`u phi vu. sa^u va`o vu`ng tro+`i Ba('c Vie^.t. Ca'c he^. tho^'ng ddu+o+`ng ho?a xa (ddu+o+`ng ra^`y xe lu+?a), nha` ma'y bo+m nu+o+'c, kho than, nha` ma'y ddie^.n Cam Pha (ddi.a danh mu` mo+` vi` sa'ch Anh ngu+~ kho^ng bo? da^'u) ga^`n bie^n gio+'i Vie^.t-Hoa, va` nha` ma'y ddie^.n Uong Bi (ddi.a danh mu` mo+` vi` sa'ch Anh ngu+~ kho^ng bo? da^'u) ga^`n Ha?i Pho`ng dde^`u bi. oanh ta.c to+'i ta^'p. Lon O. Nordeen: Air Warfare In The Missile Age, tr.20).
-	Tra^.n kho^ng chie^'n dda^`u tie^n cu?a na(m 1966 xa?y ra (ta`i lie^.u kho^ng ghi nga`y tha'ng) giu+~a phi co+ loa.i F-4C cu?a Phi DDoa`n 555, thuo^.c Kho^ng DDoa`n 8 Kho^ng Qua^n Hoa Ky`, ddu.ng ddo^. vo+'i 2 phi co+ MIG-17 cu?a Co^.ng Sa?n Ba('c Vie^.t. Mo^.t ma'y bay Ba('c Vie^.t bi. ha. bo+?i ho?a tie^?n Sparrow, mo^.t chie^'c kha'c bi. ba('n no^? bo+?i ho?a tie^?n Sidewinder. Lon O. Nordeen: Air Warfare In The Missile Age, tr.20-21).
-	Tra^.n kho^ng chie^'n dda^`u tie^n cu?a ca'c phi co+ Ha?i Qua^n Hoa Ky` trong na(m 1966 (ta`i lie^.u kho^ng ghi nga`y tha'ng) dda~ xa?y ra khi ca'c khu tru.c co+ (aircraft, fighter type) loa.i F-8 Crusader ddu.ng ddo^. vo+'i 4 chie^'c MIG-17 cu?a Ba('c Vie^.t. Tra^.n kho^ng chie^'n ke^'t thu'c mau le.. Phi co+ Hoa Ky` ba('n ha. mo^.t MIG-17. Ba chie^'c co`n la.i so+. ha~i ru't lui kho?i vo`ng chie^'n. Commander Harold L. Marr tro+? tha`nh phi co^ng F-8 dda^`u tie^n cu?a Ha?i Qua^n vo+'i tha`nh ti'ch ba('n ha. phi co+ Ba('c Vie^.t tre^n vo`m tro+`i ddi.ch. Lon O. Nordeen: Air Warfare In The Missile Age, tr.21).
-	Trong na(m na`y, Ba('c Vie^.t bo^' tri' khoa?ng 5,000 loa.i su'ng pho`ng kho^ng ddu? co+? xung quanh Ha?i Pho`ng va` Ha` No^.i. Theo ta`i lie^.u cu?a John M. Van Dyke, trong quye^?n North Vietnam's Strategy For Survival, qua^n Ba('c Vie^.t dda~ dda(.t luo^n su'ng pho`ng kho^ng o+? tre^n no'c nha`, be^.nh vie^.n, co+ so+? thu+o+`ng da^n, v.v. Lon O. Nordeen: Air Warfare In The Missile Age, tr.21).