The rationale behind US troop withdrawals from Germany

For such a decision, however, there is little clarity or consensus on the real motives.

The US president initially disclosed two of his frustrations with the current German government, headed by Angela Merkel, following his charge of their being "delinquent" at a rally on 20 June.

The president griped that Germany has not reached its Nato defence spending pledges of 2 percent of national GDP, and that Germany is still funding the Russian-German Nord Stream 2 pipeline which will supply Europe with energy from Russia.

Both of these accusations have undercurrents of realist foreign policy, as did the additional rationale provided by the White House's national security advisor, Robert O'Brien, in the Wall Street Journal the following day.

O'Brien confirmed that the withdrawal is partially due to Germany not doing their "fair share" of defence spending and its continued economic ties with Russia.

He also suggested that the redeployment was to "counter China and Russia," and that Washington was keen to pressure the German government into choosing a European company for its 5G communications network, and not Huawei, the Chinese owned telecommunications firm that the US recently declared a national security threat.

If the troop withdrawal, or threat thereof, is intended to counter "two great-power competitors" and stiff-arm a European ally into following US policy, it would highlight a strong realist motivation behind the current US administration's foreign policy, one that is also shared within American academic circles.

Indeed in 2019, John Haines, a senior fellow with the Foreign Policy Research Institute, described Germany as "an egregious free-rider when it comes to national defence spending", whilst also voicing realist concerns over growing relative Russian power, stating that "fewer than half of frontline Nato members spend proportionately even half of what Russia does on defence".

However, alternative possible motivations have been raised for this policy, some with less emphasis on realist understandings of power politics.

One potential factor behind the president's statement could be playing to the home crowd with the presidential election looming in November this year, highlighted by the chair of the Bundestag's foreign affairs committee, Norbert Röttgen.

Another suggestion, also linked to elections, drew a connection between Trump's recent proposal of redeploying some personnel in Poland with Polish president Andrej Duda's recent visit to Washington and ongoing re-election campaign.

It would appear that the realist foreign policy of Washington is infectious, however, as Duda later warned potential Polish enemies of not receiving a "soft landing" upon initiating an attack.

Finally, another view, expressed by former US ambassador to Germany, John Kornblum, is that this proposal is rhetoric, without any substantial intention behind it.

If this were the case, it would lend credence to the idea that Washington is using the withdrawal as a threat to coerce Angela Merkel to cease ties with Russia and China, the US' main rivals when viewing the international scene from a realist perspective.

Interestingly, regardless of the initial motivation, the US' recent appraisal of Germany's foreign commitments does illuminate an interesting area for EU policy improvement.

Strangely enough, O'Brien states his frustration at Germany only spending 1.4 percent of their GDP on defence, although this figure is based on a 2019 NATO projection.

The actual spending by Germany sits lower at 1.3 percent of GDP, 0.7 percentage points off where they need to be by 2024, which the country states will be reached by 2031.

Considering the EU and Nato share 22 member states, it seems unusual for Germany to be so lackadaisical in achieving an international commitment, although the reprioritisation of spending and global economic contraction resulting from Covid-19 will likely assuage potential critics of this failure.

Ultimately, this difference between US expectations and German execution could come down to broad divergences in public opinion and cultural priorities, or it could represent a worrying indicator of the transatlantic relationship to come.

It appears that the US leadership is currently more focussed on electioneering and leveraging political compliance than it is on maintaining international security, although the fact that the public, experts and politicians alike cannot understand the actual rationale is perhaps the greatest cause for concern.

Maybe, as German foreign minister Heiko Maas suggests, the Atlantic really is widening, and realist foreign policy is behind it.