Alaska was not well-defended during the Cold War.
If your impression of the border between the Soviet Union and the United States along the Bering Strait is something akin to the inter-German border, allow me to dissuade you. There were no batteries of guns or offensive missiles along the Bering Strait and no significant military or naval force for hundreds (and sometimes thousands) of miles.
The American military presence in Alaska was a tripwire for the defense of the Lower 48, not a shield of defense for the 49th state or northern Canada.
Immediately after the end of the campaign to recapture the western Aleutians from the Japanese in 1943, the military presence in Alaska declined markedly but did not entirely disappear. Alaska was still a significant conduit for Lend-Lease aid to the Soviet Union. Military ships sailed north from California, skimmed Alaska's southern coast, and were transferred to the Soviet Union at Cold Bay, on the Alaska Peninsula. Thousands of aircraft were delivered to the Soviet Union via a string of airstrips that stretched from Montana to Nome and then to a similar Soviet string in Siberia. The transfer was made in Fairbanks, hundreds of miles from the Bering Sea, and Soviet pilots flew their new aircraft from Fairbanks and into Siberia.
After autumn 1945, this system came to a close and was dismantled. A few airstrips were kept in operation, but the military largely evacuated Alaska. In the years immediately following the end of the war, one of the most significant military operations was an air-sampling mission conducted with reconnaissance aircraft based at Eielson Air Force Base. It was one of those aircraft that in 1949 detected fallout from the first Soviet atomic bomb test.
That test changed everything for the United States. Americans had hoped that the end of the war would bring peace, and that the American atomic monopoly would mean a permanent defense without a large military outlay. It was thought that nuclear weapons would serve as a permanent deterrent and that the United States would no longer need a large conventional military.
The development of Soviet nuclear weapons meant that the United States now needed to know of an impending Soviet attack in order for deterrent to still work. Deterrent wouldn't work if the American nuclear arsenal could be destroyed in a Pearl Harbor-style attack.
In light of this, the U.S. military began developing plans for a radar network and a system of fighter bases in Alaska. In developing this, planners drew upon the significant success of the UK during the Battle of Britain. The "Permanent Radar System" of 1949 envisioned early warning stations along the coast, coordinated by intermediate ground-control stations, with master stations at the sites of the airfields, allowing aircraft to successfully scramble and intercept.
Here's a three (1, 2, 3 )-part series from the New York Times in 1950 explaining the situation. I've used images rather than the Times' archives so I can share the images that accompany the story.
Time was of the essence in these cases. Here's a 1962 document pulled from the Air Force archives at Elmendorf Air Force Base. It shows that by that time, the Air Force expected to have less than an hour's worth of warning before a bomber reached the state's main population and military centers.
The outbreak of the Korean War definitively ended the notion that nuclear weapons eliminated the need for a conventional military. However, cost concerns and the logistical difficulties involved with construction in Alaska meant that by August 1951, the permanent system of 1949 was still only partially built. It wasn't until 1954 that the permanent system was fully implemented, with a network of coordination stations, radar systems and fighter bases.
By this time, however, the Soviet threat had changed. Soviet bomber technology had advanced to the point that incoming aircraft no longer needed to fly the absolute shortest route to the Lower 48. Cross-polar routes were now possible, so the United States and Canada cooperated in the construction of the Distant Early Warning Line of radar stations across Alaska's North Slope. These stations were later joined by others along Alaska's west coast and the Aleutians.
While fighters were envisioned as the biggest arm of defense, they were joined by land-based anti-air weapons, too. In the early 1950s, 90mm antiaircraft guns were mounted around Fairbanks and Anchorage. These were replaced by surface-to-air missile batteries, most notably the Nike stations that surrounded those two cities. Alaskan surface-to-air defense relied upon the "island" strategy whereby missiles would protect only Fairbanks and Anchorage, defending those two cities and their four military bases nearby.
The Nikes had low levels of success in tests, but in wartime they could have been armed with atomic warheads, greatly increasing their ability to defend against air attack. The same was true for Alaska's fighter squadrons, which had nuclear-tipped air-to-air missiles available.
Again, however, technology changed the perceived threat. By the late 1950s, when the DEW Line reached its peak, the launch of Sputnik was another shock to the system. The missile threat changed the map again. Curtis LeMay, Chief of Staff of the U.S. Air Force, believed that missiles were the future of nuclear combat. He thought that missiles made bombers obsolete because they could be launched (and a warhead delivered) before any bomber could take off from its base.
After Sputnik, he began a general drawdown of the fighter presence in Alaska. The radar stations and their vast communication network remained, the better to provide early warning for the Lower 48, but by 1962, there was only a single fighter squadron in Alaska, the 317th Fighter-Interceptor Squadron, and it used obsolescent F-102 Delta Dagger aircraft with insufficient range for Alaska's long distances.
LeMay's actions were opposed by Gen. Frank Armstrong, the commander of military forces in Alaska, who denied that bombers were irrelevant and supported the preservation of a strong fighter aircraft presence in Alaska. After some pretty heated words in the press, he was forced to retire from his position.
Alaska's air defenses reached a low ebb in 1963, when a pair of Soviet bombers successfully penetrated American airspace, overflew southwest Alaska and withdrew before the F-102s of the 317th FIS could intercept them. This embarrassing performance by the American interceptors (and the subsequent public and political outcry from Alaskans) led the Air Force to begin rotating squadrons of more modern aircraft north to Alaska on rotation. This rotation reached full swing during the Vietnam War, and the 317th FIS was disbanded in 1969.
Meanwhile, Alaska's radar network continued to be modernized. Improved radar technology meant the number of stations could be scaled back and the system kept its form in this scaled-back version until the end of the Cold War. A missile-detection radar was installed in the early 1960s at Clear Air Force Station in Alaska's Interior, and satellite-detecting radars were installed at Shemya (in the Aleutians) and at Cape Chiniak in Kodiak. Other satellite downlink stations took data from launch-warning satellites installed to detect the flare of a soaring missile engine.
The Offensive Defense
Throughout the Cold War, and particularly in the early Cold War, Alaskans and their politicians advocated for the United States to maintain a strong offensive nuclear presence in the territory and (after 1959) state. Reading through the papers of Alaska's Congressional delegation, I was struck by the number of letters pleading for the establishment of a Polaris submarine base to house submarines carrying nuclear weapons.
Later in the Cold War, it was advocacy for rail-bound MX-Peacekeeper missiles that seemed to drive the letters.
In the early years of the Cold War, the United States forward-based nuclear-armed bombers in Alaska, particularly at Elmendorf and Eielson Air Force bases. This was out of necessity: Until the development of the B-52 and midair refueling, American atomic bombers did not have the range to reach targets in the Soviet Union and return to bases in the Lower 48.
Bases in Alaska served the same role that bases in Spain (Rota), Libya (Wheelus), Turkey and other places did. They allowed places for bombers to stage in advance of a strike. This was less than desirable from a military standpoint, because it left those bombers vulnerable to a preemptive attack in a Pearl Harbor-style assault. For security reasons, it was better to base bombers in the Lower 48, where distance would allow early warning and countermeasures preventing a sudden attack.
Thus, as bomber technology improved, airborne tankers took the place of forward-based bombers in most circumstances in Alaska. The bombers and their crews were in places like North Dakota and Arkansas, not in Alaska (by and large).
The same was true for missiles. The United States explored the possibility of basing intercontinental or intermediate-range missiles in Alaska, but high costs and the lack of early warning nixed the idea. The speedy development of more advanced missiles also contributed to the lack of a permanent missile base in Alaska. By the time such a base reached the planning stages, long-ranged missiles could reach the Soviet Union from the Lower 48.
The Soviets proved the American decision correct when they attempted to construct an ICBM base at Anadyr, not too far from Alaska. The base, which entered service in 1963 at extraordinary cost, was decommissioned before 1970 due to environmental factors and the development of longer-ranged missiles that rendered it obsolete.
As I posted previously, there were nuclear weapons in Alaska: bombs at Elmendorf and Eielson, air-to-air missiles, air-to-surface missiles, as well as atomic depth charges, atomic artillery shells, and atomic bazookas.
Naval defense was practically nonexistent in Alaska during the Cold War, part of a deliberate policy intended (again!) to prevent another Pearl Harbor. For example, in 1962 during the Cuban Missile Crisis, the U.S. Navy had bases at Adak in the Aleutians and in Kodiak. The sole "warship" in the Navy's Alaska district was a landing ship.
In the event of war (taken from plans in place at the time of the Cuban Missile Crisis), the Navy's strategy called for a submarine tender to sail north to Kodiak to provide support for submarines deployed from Hawaii, which would be arrayed off Petropavlovsk. A carrier air group would sail north to provide support as soon as practicable. The first carrier to practice this was the Ranger in 1962, which stopped in the Bering Sea as it returned to California from a deployment in Japan, but according to members of the crew who I've exchanged emails with, the Bering Sea was simply too rough for exercises, and the carrier group departed with no significant practice.
On land, there was no significant military presence on or near the border. Fort Wainwright (in Fairbanks) and Fort Richardson (in Anchorage) are hundreds of miles away from the border. Intelligence summaries in the early 1960s anticipated the possibility of Soviet airborne assaults on locations in Alaska, but with the benefit of hindsight and Soviet sources, I find those analyses wrong in the event of a sudden war.
The general policy throughout the Cold War was that in the event of a significant land invasion of Alaska, the U.S. Army (with support from the Eskimo Scouts of the Alaska National Guard) would conduct a fighting withdrawal if necessary. A guerilla and stay-behind campaign would begin -- aided by agents recruited by the FBI -- while American and Canadian forces massed in the Yukon for a counterattack.
By "protected," do you mean "defended"? If so, I'm happy to answer.
As a Canadian, I would like to add a little info I've heard over the years.
One of the reasons the "Alaskan Highway" was built, was if Alaska ever got invaded the US military could quickly send troops and tanks North asap, the highway goes right through Alberta and many believed that the USSR would simply bypass Alaska, and the mountains and come down through Alberta, as it's a faster and much easier way to Washington.
NORAD, sits exactly where it is because it can quickly defend both Canada, and Alaska from air strikes.
Back in the 80's when I was a kid, we saw cruise missiles being tested across Alberta. Everyone said it was due to Alberta having the same landscape as Siberia. But I believe they were testing just how effective they would be stopping a Soviet invasion from Alaska, through Alberta.
