According to security experts, the German armed forces are too weak to meet their obligations towards their allies, not least because next year they will take command of NATO's rapid response force for crises.
The pressure on Berlin is mounting after a series of revelations revealed the German military as one of the least suited to NATO's needs, despite its economic weight.
"The readiness of the German army is abysmal," said Jorge Benitez, a NATO expert at the Atlantic Council in Washington. "For years, German leaders have known that the main elements of their armed forces, such as tanks, submarines and fighters, are not fully operational and can not be used for real military missions."
Military dysfunction is likely to re-emerge as a point of next friction between Berlin and Washington when President Donald Trump attends the NATO summit in July.
Berlin's persistent shortcomings and resistance to meeting NATO's spending targets could further weaken relations with Washington and risk a stalemate that could possibly challenge the unity of the alliance and the American commitment to it.
Trump, long skeptical of NATO's value, has fixed his attention on Germany as a free-rider when it comes to security: the alliance "helps them much more than it can help us," Trump said last December.
Among the failures: none of the German submarines is operational, only four of its Eurofighter 128 jets are ready for combat and the army is running out of dozens of tanks and armored vehicles needed for NATO missions.
In addition, the troops are short of fundamental principles: body armor, night vision equipment and clothing for the cold.
The situation is so disastrous that 19 helicopter pilots from the German Bundeswehr have been forced to hand over their flight licenses due to lack of training time.
The reason: not enough helicopters to pilot pilots.
A low priority
The internal military documents and the investigations of the German media have highlighted the inability of Berlin to reverse the constant shift of readiness to combat, which concerns the concerns of a more aggressive Russia that increases the demand for more agile NATO armies.
Yet there is little sign that Germany's political leadership will do much, with the parliament stuck in partisan budget disputes over defense spending.
Defense Minister Ursula von der Leyen said on Monday that it expects military spending to reach 1,5% of economic output in the 2025, which means that unless a dramatic change occurs, Berlin will give up on a commitment it has made to United States and NATO allies in the 2014 when members agreed to reach the 2 percent within a decade.
The Christian Democratic Union of German Chancellor Angela Merkel has historically been the main party advocating more defense spending. On Monday, Merkel admitted that German "credibility" was at stake and that defense spending must increase.
Yet Merkel also promised during last year's election campaign that spending on Germany's welfare state - including a national pension plan, public health care and nursing, generous unemployment benefits, social assistance and education - would continue to prevail over the increase in military spending required by the defense ministry and NATO.
Von der Leyen calls for an increase of $ 14 billion compared to current budget plans. The request is addressing the resistance of the German finance ministry, which has planned an increase of approximately 6,6 billion dollars over a four-year period.
The office of Von der Leyen defined the current plan "inadequate in view of the enormous needs accumulated and of the modernization required, especially in the medium term".
While Germany has slowly increased defense spending in recent years, the budget of 37 billions of dollars is only 1,24 percent of its GDP.
"Germany has the largest economy in Europe, but has continued to lift its scandalous defense problems," said Benitez. "Part of the problem is political and reflects the willingness of the German leaders to constantly inhibit defense spending for the sake of other priorities".
An obstacle to promoting defense spending could be Trump himself because he is deeply unpopular in Germany and backing him in his demands could be politically damaging to everyone.