Should the NATO allies increase their defence spending, up to a level of 5% of GDP, as President Trump has said?

Most NATO allies are in agreement: 2% of GDP is the minimum level for defence spending. But 2% is not enough for NATO to meet all its goals. No decision has been made yet about the exact percentage needed. The allies are still discussing this. It is clear, however, that investments in defence and security will have to be increased. Amid the current threats it is important to invest more money, more rapidly.