Trjtdtk

The American electorate is extremely divided over ideological lines at the moment. During the Cold War there were still divisions, but we could generally all agree that Americans were always better to deal with than the Soviets. Now that is not the case. A substantial portion of the President's base aren't at all upset (in some instances even gleeful) that the Russians interfered in the American elections since they view that as helping "their side", while folks at the far end of the other side of the spectrum have made statements equating it to an act of war. In your question there is an underlying assumption: that Americans want to do something.

On that note we can't agree that anything should be done. Not in Ukraine, and very little agreement on Syria. Venezuela currently does have a bit more support for something to be done, which I believe is because the United States has historically regarded all of the Americas as under their sphere of influence. But the U.S. track record there has hindered our ability to build consensus with other regional partners (this Wikipedia article is also a pretty good read for this point).

I don't think the U.S. is becoming more tolerant of Russian hostility, our deep political divisions are keeping us from doing much about it and Russia is taking advantage of the circumstances. Combine this point with two long wars, and there's just not any support for using military options to act as a counter balance. The current U.S. mood is much more introspective at the moment (as a whole, definitely not on an individual level).

This is a pretty broad question. If we ask more pointedly why Obama didn't intervene more in Ukraine... He told us that himself.

As Jeffrey Goldberg, The Atlantic’s editor in chief, wrote in the Obama Doctrine: “Obama’s theory here is simple: Ukraine is a core Russian interest but not an American one, so Russia will always be able to maintain escalatory dominance there.” Indeed, Obama told Jeff: “The fact is that Ukraine, which is a non-NATO country, is going to be vulnerable to military domination by Russia no matter what we do.” Despite their criticism of Obama, the Republican platform ahead of the 2016 presidential election didn’t call for U.S. weapons to be sent to Ukraine to fight Russian-backed rebels.

Now instead of vague comparisons with the cold war, I think a better one would be to ask why Roosevelt and Churchill gave up Eastern Europe to the Soviets. The answer is pretty similar, they didn't think they couldn't do much about it anyway nor did they have that much strategic interest there, unlike in Greece, where the opposite happened:

British interest in Greece was of long historical standing and
connected with its imperial foothold in the Near and Middle East, [...]
Moscow was prepared to abandon
Greece for the sake of tightening its grip on the rest of the Balkans. As
a result, the communist rebellion in Greece was doomed.

And of course, the US never gave up Latin and Central America (supporting coups there), which is not too unlike what Trump does now in Venezuela.

As for Syria, I'm not sure I can find an appropriate parallel during the cold war. (Lebanon maybe?) But after the Arab Spring in Libya, the West had lost appetite to support "moderate" islamists, only to find out that they weren't so moderate or hardly influential on the ground. And US strategic interest in Syria appears limited, compared to that of Turkey etc. At least public opinion seems to be that

President Barack Obama reiterated that the U.S. has “both a moral obligation and a national security interest in, A, ending the slaughter in Syria,” and in “ensuring that we’ve got a stable Syria that is representative of all the Syrian people, and is not creating chaos for its neighbors.”

But a New York Times/CBS opinion poll showed that almost two-thirds of Americans say the U.S. has no responsibility to address the fighting in Syria.

We'll see if the more pragmatic Trump sticks with the Kurds now that the main reason to support them (fight against ISIS) appears gone.

As for the militaristic wind of change in the past decade...

After the 2008 Russia-Georgia war, Putin likely
concluded that Russia could use hard power in its
neighborhood without the possibility of a decisive
military response from the West.

So some analysts (more than one for sure) consider that war as the catalyzing event.
There is probably some briefing or opinion poll somewhere that
says Georgia wasn't all that important to the US.

And finally, the Western response (not just to the war in Georgia, but also Ukraine etc.) has been largely based on economic sanctions. These have also been used in the cold war. And they eventually worked, but it took decades for their ultimate effect to occur. What is different from the cold war is that there seems to be more of a rift now between the US and Western Europe as to the extent of sanctions (and not just on Russia, but also Iran etc.)

The growth of Europe-Russia economic interdependencies has been played for that effect:

“It’s Diplomacy 101,” Ernest Moniz, the veteran U.S. nuclear negotiator and former Secretary of Energy under President Barack Obama, told TIME after attending several of the closed-door sessions with European diplomats. “If a wedge opens up, you exploit it. You drive it as deep as you can.”

“The Americans expect the Europeans to follow along,” says Thomas Kleine-Brockhoff, the head of the Berlin office of the German Marshall Fund of the United States. “They will find that Europe won’t.”

Many Europeans support that approach. A Pew Research survey published on Feb. 15 [2019] found that only around 10% of people in France and Germany have faith in Trump’s handling of global affairs; they are two or three times more likely to trust the leaders of Russia and China.

Trump talking of Europe as an economic enemy surely didn't help with that recent confidence slump. But the fundamentals were in place long before:

These days, there is much discussion about a new strategy of “containment” towards Russia. European policymakers are going back and reading George Kennan’s “Long Telegram” – written in 1946 and published anonymously as “The Sources of Soviet Conduct” in Foreign Affairs in 1947 – and wondering whether it is once again relevant. In it, Kennan, then a diplomat at the US embassy in Moscow and later the head of policy planning in the State Department, said the United States should “regard the Soviet Union as a rival, not a partner, in the political arena” and called for “a long-term, patient but firm and vigilant containment of Russian expansionist tendencies”. That meant “the adroit and vigilant application of counter-force at a series of constantly shifting geographical and political points, corresponding to the shifts and maneuvers of Soviet policy.”

Even during the Cold War, “containment” was a notoriously vague term. What began as an attempt to prevent further Soviet expansion later turned into a more aggressive attempt to “roll back” Soviet influence. In his memoirs, published in 1967 as the United States was escalating its involvement in Vietnam, Kennan said “containment” had been misunderstood: he had wanted to prevent Soviet expansionism using political rather than military means. There were different ideas about the focus and scope of “containment” as well as about means – thus John Lewis Gaddis, the leading historian of containment, distinguished between “symmetrical” containment (responding in kind) and “asymmetrical” containment (picking your battles). But what “containment” might mean now is even less clear than it was during the Cold War.

The biggest difference between the Cold War and the post-post-Cold War is the extent of economic interdependence between Russia and the West – and in particular between Russia and Europe. This is partly a consequence of globalization. But it was also a deliberate strategy. For the last twenty years or so, the West has expanded trade and tried to integrate powers such as Russia and China into the international system. This in turn was based on two assumptions. The first was that economic interdependence would lead gradually but inexorably to democratisation. The second was that economic interdependence would turn these powers into “responsible stakeholders”, as Robert Zoellick put it in a speech on China in 2005. The greatest achievement of this approach was Chinese and Russian accession to the World Trade Organization (WTO).

[...]

After the annexation of Crimea, Russia was immediately rejected from the G8. As Russia has destabilized eastern Ukraine, the West has also gradually imposed remarkably tough economic sanctions. The imposition of sanctions has been led by the United States, which had much less trade with Russia than Europeans and therefore less to lose. But Europeans have reluctantly followed and imposed sanctions of their own, especially after Flight MH17 was shot down in July – a kind of tipping point for public opinion in countries such as Germany. The question now is what happens next if Russian expansionism continues. Do we continue to unwind economic interdependence until it reaches the levels that existed with the Soviet Union during the Cold War (or with Iran now)?

The post-2014 sanctions have had as a result a reduction in this interdependence:

Note however that 2017 saw a 20% rebounce in EU-Russia trade, so that graph is somewhat misleading as to the magnitude of the long term impact of sanctions (the slide has some sectoral data, so I thought it interesting, well as going back a fair bit for perspective). The short-term trend with 2017 included (no newer data seems available just yet, it gets updated in April), looks like

Likewise European FDI (Foreign Direct Investment) in Russian (which was about 75% of total FDI in Russia in 2014) also sank in 2015 to about half its 2013 figure (same source as that graph). And some of the effects were severe for Russia, e.g. 50% devaluation of the Rubble in 2014.

The reduced economic ties actually make it easier for future action (economic of otherwise) against Russia to be taken. Whether it will get back to cold-war levels... is a tough question (and depends on many factors), but it's clearly something that won't happen overnight. And those ties act as a brake on any radical idea of containment.

Numerous reasons. For start, the United States has been in a state of war since September 2001, and Obama was characterized by an avoidance of further war during his presidency (He is to date, the only U.S. President to have served his total presidency at War). There are many sentiments on both sides of the aisle that just want to avoid wars and strong anti-interventionalist movements (The Libertarian Right tends to be opposed to war for reasons other than defense of self or allies, the left just tends towards no wars period). This played a part in the Ukraine situation.

With the Syrian Civil war, the United States never loved the Syrian Government and by the time the idea was considered, the anti-government forces included terrorist organizations including remnants of Al-Quadia. The political sentiment moved from fighting a Russian backed Syrian Government to a policy more akin to the old man from the recent Godzilla movie "Let them fight." There's not much to be one by propting up an anti-U.S. rebellion movement fighting against an Anti-U.S. government forces.

The Maduro thing is relatively recent and the U.S. policy is to support the opposition leader over Maduro, so we'll have to wait and see. It doesn't help that Russia's active involvement occurred around the same time as a hurricane of domestic stories hit the U.S. (The Mueller Report's findings, the Avenatti arrest, and the Jessui Smollett charges being dropped) which have occupied most news network's general reporting.

The Cyber Security issues are hard to peg down, as they tend to be covertly dealt with so as to not reveal the new protections and better investigate. Because of this, it could be a great many battles are fought on this issue, but the battles are not discussed (The First Cold war was a very busy time for intelligence communities and could be said that it was a war of spies more than anything else... a great deal of winning that conflict was just gathering information on what the adversary was doing).

During the Trump presidency, it's due to how the Constitution has divided power between Congress and the President.

Congress has very limited powers in international affairs:

To regulate Commerce with foreign Nations...

To declare War...

Compare to the President's powers:

The President shall be Commander in Chief of the Army and Navy of the United States...

He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties...

...he shall receive Ambassadors and other public Ministers...

In short, Congress has one thing they can do in response to Russian actions: they can impose economic sanctions. They've also got the power to declare war on Russia, but they don't have the ability to prosecute that war -- commanding the military is a power reserved for the President.

Compare that to the President's powers. He can negotiate diplomatic agreements either with Russia or with third parties. He can engage in military action short of war, including dispatching troops to countries threatened by Russia. He can cut off (or threaten to cut off) diplomatic relations.

The Constitution places almost all the power to confront a country in the hands of the President. With Trump favorably inclined towards Russia, that greatly limits what the rest of the country can do.

There is a joke on Chinese websites:

"Why did you attack (some places that US had a war with)?"

"We suspected them of having mass destruction weapons."

"But why don't you attack Russia?"

"They really do have mass destruction weapons.

For #2, the only government that is proven having been doing cyber attacks to a foreign country (as I know) is the US government. It's almost impossible to confirm an attack that involves computers in a country really organized by its government, unless a government document says so.

For others, they all involve instability of a 3rd country. They may not really care too much about what is the absolutely best solution for the 3rd country. But in the worst case, something like ISIS appears. If the US behavior is acceptable, we could only say nobody is approaching an ideal solution. We can't say the US is all right, because the other side did at least one tiniest thing wrong. Russians may have done something comparable to them, not much worse, but just on a different stance.

There is no reason that Russia would ever evolve into a religious or terrorist country. Neither does it have reasons to allow Crimea turning into such a place.

Just nobody would be able to turn a 3rd country into the best developed place very soon. And nobody would want them turning into the worst chaos. Unfortunately for the people there, other factors in between are just details for the big countries. TL;DR as the joke said, it's just not very beneficial being too aggressive to Russia.