Defence ministers from the United States-led Nato military alliance in Europe are gathering today in Brussels to assess progress on improving security arrangements on their continent.

In theory, this should be an easy meeting; tensions between the Trump administration and Europe over how much each Nato nation contributes to Europe's defences is over, and all member states pledged to increase their military spending and capabilities.

But disputes about Nato's future military posture persist, while Britain's planned departure from the European Union adds further strain, by encouraging European governments to push for additional security structures.

American defence officials are delighted with their success in pushing each Nato member state to spend at least 2 per cent of their gross domestic product on defence.

Yet, the biggest task for the Americans now is to persuade Germany, Europe's biggest and wealthiest nation, to increase its defence spending. The Germans currently spend €37 billion (S$58.4 billion) yearly on their military - just under 1.3 per cent of its GDP.

Facing a general election this year, German Chancellor Angela Merkel persuaded her country's partners not to raise the issue at earlier Nato meetings. But now that the ballots are over, the US and a number of European Nato members are looking to her for an early financial commitment to the military.

Deeper structural reforms are also anticipated with the alliance. Tensions with Russia in the wake of the war in Ukraine and the latest exercises undertaken by Russian troops have heightened fears that current plans for US troops to reinforce Europe in times of need are vulnerable.

General Petr Pavel, head of Nato's military committee, is proposing a new allied command, tasked with ensuring that the vital lines of supplies between North America and Europe over the Atlantic are strengthened. "If we look at the growing capabilities of countries like Russia and China, with a global reach, it is quite obvious that maritime lines of communication have to be protected," General Pavel said yesterday.

This was one of the first public mentions of China as a potential adversary from a senior Nato military official, and it may have been prompted by the presence of Chinese military ships in a Russian-led naval exercise earlier this year in the Baltic Sea, a sensitive Nato supply region.

If a new command is created this week, it will represent a reversal of Nato's previous policies, which consisted of closing down many Cold War-era structures.

But a far livelier discussion is likely to be prompted today by an initiative led by France and Germany to create a new framework of defence pooling of resources within the EU, named Permanent Structured Cooperation, or Pesco.

In theory, that makes sense: With Britain soon to leave the EU, there is nothing to prevent the rest of the EU member states from cooperating more closely in Europe-wide frameworks, something Britain has vetoed in the past.

At least officially, the Pesco initiative does not cut across Nato's purpose, but merely enhances it by ensuring, for instance, that the Europeans spend their defence money more efficiently.

Pesco also avoids the creation of an alternative military alliance in Europe - it is available to any EU nation which wants to join, without duplicating Nato's structures.

But as is often the case in Europe, the initiative is stirring up great controversy. Critics of the Pesco proposal fear it is merely another ill-disguised attempt by Germany and France to tell others what to do.

Defence specialists also question whether the pooling of resources will result in real savings since a European decision to buy weapons from only one supplier - invariably likely to be a European one - may increase costs by creating monopoly manufacturers.

The French and the Germans claim that a "fair number" of EU states will sign up to their new defence concept this week. But German Defence Minister Ursula von der Leyen has not helped the cause of European unity by recently criticising the Polish government for its domestic policies.

Mrs von der Leyen claims she was misquoted. However, the Poles are outraged, and for good reason - the patronising attitude that Western European governments often adopt towards their Eastern partners remains the biggest stumbling block to Europe's defence arrangements.