The USA produces more Oil then does Russia and with the Middle East firmly under the US umbrella , the US Government wants to ensure that US controlled sources provide Oil to Western Europe. This means more profits for US Corporations and ensures West Europe remains a vassal state.
Increasing spending to 4 percent GDP even when there no real military threat is a Trojan Horse. This Military spending in the USA is what led to them dismantling Social Program spending. If European Countries spent 4 percent GDP on Military spending they would have to make cuts elsewhere. The prime target would be Health Care spending wherein those systems would be dismantled for “budgetary reasons” in favor of the for profit model.
At the same time a 2 percent of GDP increase in Military spending would mean in sum total some 420 BILLION more in profits to the Corporations that produce Arms. With that much of a nations wealth invested in making weapons , those firms then become “Too big to fail” as entire economies will be built around Military spending. Europe would be faced with a perpetual arms race building and buying weapons they do not need simply because the Economy will be so reliant on Military spending to provide jobs.
That added 420 billion in spending finds its way into the pockets of some small few whereas Social program sending on things like health care and poverty reduction schemes goes into the pockets of the many.
IN short none of this has anything to do with National Security and everything to do with filling the pockets of the 1 percent with even more wealth.