European members of NATO have agreed to buy planes and submarines jointly and possibly open a new command headquarters for elite troops after the United States threatened to curtail its support unless Europe increased military spending by the end of the year.

At Thursday's signing ceremonies in Brussels, defence ministers from France and Germany said they would buy Lockheed Martin C-130J Super Hercules transport planes, while Germany, Belgium and Norway will join a Netherlands-led fleet of Airbus A330 tanker planes.

A new command centre is also planned for Dutch, Belgian and Danish special forces that could be used by other NATO nations and which many countries outside the main European military powers of Britain, France and Germany do not have.

The location of the new headquarters has not been decided, a NATO official said.

Other plans include Norway and Germany buying a new class of submarines, known as U212As, that more effectively detect, track and fire at enemy submarines and ships on the water.

Germany also agreed to joint training and deployments of land forces with the Czech Republic and Romania, with both countries set to provide a brigade of several thousand troops for a larger division under German leadership.

"This multinational cooperation through NATO is a clear way for countries to significantly improve their armed forces while ensuring the greatest value for money for their taxpayers," said Rose Gottemoeller, NATO's deputy secretary-general.

Jim Mattis, the new US defence secretary, warned NATO allies on Wednesday that they must pay more towards their own defences or potentially see less support from the US.

Jens Stoltenberg, NATO secretary-general, said allies faced a "more demanding and challenging security environment" that the alliance needed to respond to.

"This is a way to make what we do more efficient, and increase output," he said of the agreements signed.

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The letters of intent, although not legally binding, are the latest sign that European allies are starting to end years of competing national strategies that have left Europe reliant on the US to provide such basics as refuelling combat planes in the air.

Duplication is another problem, with EU militaries owning 19 types of armoured infantry fighting vehicles, compared with one in the US, while wasted funds amount to about $26bn a year, according to European Commission data.

As part of a broader push to revitalise European defence cooperation following Russia's 2014 annexation of Crimea and the rise of ISIL-linked violence on Europe's borders, France agreed to allow Belgian and Dutch jets to fly into its airspace in the case of a conflict with a foreign threat.

This means that a Belgian jet pursuing an enemy plane would no longer have to turn back at the French border.

The Russian factor

Al Jazeera's Neave Barker, reporting from Brussels, said the gathering was a chance for NATO members to find out how committed the US is to the bloc.

"It was also a chance to find out a little bit more about the new closeness between the Kremlin and Washington," he said.

For his part, Mattis said on Thursday that Russia would remain at arms length in terms of military cooperation.

"We are not in a position right now to collaborate on a military level, but our political leaders will engage and try to find a common ground," he said.